! ========
! controls
! ========


! specifications for starting model
! =================================

      ! NOTE: if you are loading a saved model,
      ! then the following initial values are NOT USED to modify the model.
      ! in particular, you cannot use these to change Y or Z of an existing model.
      ! if you want to do that, see ``star_job.defaults`` controls such as ``change_Y``.
      ! however, these are reported in output as the initial values for the star.


      ! initial_mass
      ! ~~~~~~~~~~~~

      ! initial mass in Msun units.
      ! can be any value you'd like when  you are creating a pre-main sequence model.

      ! NOTE: this is not used when loading a saved model.
      ! however is reported in output as the initial mass of the star.
      ! don't let that confuse you.

      ! if you are loading a ZAMS model and the requested mass is in the range of
      ! prebuilt models, the code will interpolate in mass using the closest prebuilt models.
      ! if the requested mass is beyond the range of the prebuilt models, the code will
      ! load the closest one and then call "relax mass" to create a model to match the request.
      ! the prebuilt range is 0.08 Msun to 100 Msun, so the ``relax_mass``
      ! method is only used for extreme cases.  There are enough prebuilt models that the
      ! interpolation in mass seems to work fine for many applications.

      ! ::

    initial_mass = 1


      ! initial_z
      ! ~~~~~~~~~

      ! initial metallicity for create pre-ms and create initial model
      ! ``initial_z`` can be any value from 0 to 0.04

      ! not used when loading a saved model.
      ! however is reported in output as the initial Z of the star.

      ! however, if you are loading a zams model,
      ! then ``initial_z`` must match one of the prebuilt values.
      ! look in the ``'data/star_data/zams_models'`` directory
      ! to see what prebuilt zams Z's are available.
      ! at time of writing, only 0.02 was included in the standard version of star.

      ! ::

    initial_z = 0.02d0


      ! initial_y
      ! ~~~~~~~~~

      ! initial helium mass fraction for create pre-ms and create initial
      ! (< 0 means use default which is 0.24 + 2*initial_z)

      ! not used when loading a saved model or a zams model.
      ! however is reported in output as the initial Y of the star.

      ! NOTE: this is only used for create pre-main-sequence model
      ! and create initial model, and not when loading a zams model.

      ! ::

    initial_y = -1


      ! initial_he3
      ! ~~~~~~~~~~~

      ! initial mass fraction of he3. Must be smaller than initial_y.
      ! (< 0 means use default which is taken as solar scaled such
      ! that he4/he3 has the same value as the Sun)

      ! not used when loading a saved model or a zams model.

      ! ::

    initial_he3 = -1

! controls for output
! ===================


      ! terminal_interval
      ! ~~~~~~~~~~~~~~~~~

      ! write info to terminal when ``mod(model_number, terminal_interval) = 0``.
      ! note: this replaces the obsolete control ``terminal_cnt``.

      ! ::

    terminal_interval = 1


      ! write_header_frequency
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! output the log header info to the terminal
      ! when ``mod(model_number, write_header_frequency*terminal_interval) = 0``.

      ! ::

    write_header_frequency = 10


      ! extra_terminal_output_file
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if not empty, output terminal info to this file in addition to terminal.
      ! this does not capture all of the terminal output -- just the common items.
      ! it is intended for use in situations where you cannot directly see the terminal output
      ! such as when running on a cluster. If you want to be able to monitor
      ! the progress for such cases, you can set ``extra_terminal_output_file = 'log'``
      ! and then do ``tail -f log`` to view the terminal output as it is recorded in the file.

      ! ::

    extra_terminal_output_file = ''


      ! terminal_show_age_units
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! terminal_show_timestep_units
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! terminal_show_log_dt
      ! ~~~~~~~~~~~~~~~~~~~~
      ! terminal_show_log_age
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! options are 'years', 'yrs', 'days', 'secs', or 'seconds'
      ! this replaces the old controls terminal_show_age_in_years & terminal_show_age_in_days

      ! ::

    terminal_show_age_units = 'years'
    terminal_show_timestep_units = 'years'
    terminal_show_log_dt = .true.
    terminal_show_log_age = .false.


      ! num_trace_history_values
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! any valid name for a history data column, such as ``surf_v_rot``
      ! for example if you have rapid rotation at the surface,
      ! you might want to try something like this:

      ! ::

      !     num_trace_history_values = 7
      !     trace_history_value_name(1) = 'surf_v_rot'
      !     trace_history_value_name(2) = 'surf_omega_div_omega_crit'
      !     trace_history_value_name(3) = 'log_rotational_mdot_boost'
      !     trace_history_value_name(4) = 'log_total_angular_momentum'
      !     trace_history_value_name(5) = 'center n14'
      !     trace_history_value_name(6) = 'surface n14'
      !     trace_history_value_name(7) = 'average n14'

      ! value must be less than or equal to 10

      ! ::

    num_trace_history_values = 0


      ! trace_history_value_name(:)
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! write values to terminal

      ! ::

    trace_history_value_name(:) = ''


      ! photo_directory
      ! ~~~~~~~~~~~~~~~

      ! directory for binary snapshots used in restarts

      ! ::

    photo_directory = 'photos'


      ! photo_interval
      ! ~~~~~~~~~~~~~~

      ! save a photo file for possible restarting when ``mod(model_number, photo_interval) = 0``.
      ! note: this replaces the obsolete control ``photostep``.

      ! ::

    photo_interval = 50


      ! photo_digits
      ! ~~~~~~~~~~~~

      ! use this many digits from the end of the ``model_number`` for the photo name

      ! ::

    photo_digits = 3


      ! log_directory
      ! ~~~~~~~~~~~~~

      ! directory for data files about the run

      ! ::

    log_directory = 'LOGS'


      ! do_history_file
      ! ~~~~~~~~~~~~~~~

      ! a history file is created if this is true

      ! ::

    do_history_file = .true.


      ! history_interval
      ! ~~~~~~~~~~~~~~~~

      ! append an entry to the history.data file when ``mod(model_number, history_interval) = 0``.

      ! ::

    history_interval = 5


      ! star_history_name
      ! ~~~~~~~~~~~~~~~~~

      ! name of history file

      ! ::

    star_history_name = 'history.data'


      ! star_history_header_name
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! If not empty, then put star history header info in ``star_history_name`` file.
      ! In this case the history file has only data, making it easier
      ! to use with some plotting packages.

      ! ::

    star_history_header_name = ''


      ! star_history_dbl_format
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! format for writing reals to ``star_history_name`` file

      ! ::

    star_history_dbl_format = '(1pes40.16e3, 1x)'


      ! star_history_int_format
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! format for writing integer to ``star_history_name`` file

      ! ::

    star_history_int_format = '(i40, 1x)'


      ! star_history_txt_format
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! format for writing characters to ``star_history_name`` file

      ! ::

    star_history_txt_format = '(a40, 1x)'


      ! write_profiles_flag
      ! ~~~~~~~~~~~~~~~~~~~

      ! profiles are written only if this is true

      ! ::

    write_profiles_flag = .true.


      ! profile_interval
      ! ~~~~~~~~~~~~~~~~

      ! save a model profile info when ``mod(model_number, profile_interval) = 0``.

      ! ::

    profile_interval = 50


      ! priority_profile_interval
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! give saved profile a higher priority for retention when
      ! ``mod(model_number, priority_profile_interval) = 0``.

      ! ::

    priority_profile_interval = 1000


      ! profiles_index_name
      ! ~~~~~~~~~~~~~~~~~~~

      ! name of the profile index file

      ! ::

    profiles_index_name = 'profiles.index'


      ! profile_data_prefix
      ! ~~~~~~~~~~~~~~~~~~~

      ! prefix of the profile data

      ! ::

    profile_data_prefix = 'profile'


      ! profile_data_suffix
      ! ~~~~~~~~~~~~~~~~~~~

      ! suffix of the profile data

      ! ::

    profile_data_suffix = '.data'


      ! profile_data_header_suffix
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If not empty, then put profile data header info here.
      ! In this case the profile data file has only data, making it easier
      ! to use with some plotting packages.

      ! ::

    profile_data_header_suffix = ''


      ! profile_dbl_format
      ! ~~~~~~~~~~~~~~~~~~

      ! format for writing reals to profile file

      ! ::

    profile_dbl_format = '(1pes40.16e3, 1x)'


      ! profile_int_format
      ! ~~~~~~~~~~~~~~~~~~

      ! format for writing integers to profile file

      ! ::

    profile_int_format = '(i40, 1x)'


      ! profile_txt_format
      ! ~~~~~~~~~~~~~~~~~~

      ! format for writing characters to profile file

      ! ::

    profile_txt_format = '(a40, 1x)'


      ! max_num_profile_zones
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! if ``nz > this``, then only write a subsample of the zones.
      ! only used if > 1

      ! ::

    max_num_profile_zones = -1


      ! max_num_profile_models
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Maximum number of saved profiles.
      ! If there's no limit on the number of profiles saved,
      ! you can fill up your disk -- I've done it.
      ! So it's a good idea to set this limit to a reasonable number such as 20 or 30.
      ! Once that many have been saved during a run, old ones will be discarded
      ! to make room for new ones.
      ! Profiles that were saved for key events are given priority
      ! and aren't removed as long as there
      ! is a lower priority profile that can be discarded instead.
      ! Less than zero means no limit.

      ! ::

    max_num_profile_models = 100


      ! profile_model
      ! ~~~~~~~~~~~~~

      ! save profile when ``model_number`` equals this

      ! ::

    profile_model = -1


      ! profile_header_include_sys_details
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if this is true, profile header includes strings for compiler, build, etc.

      ! ::

    profile_header_include_sys_details = .true.


      ! write_model_with_profile
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! if this is true, models are written at same time as profiles

      ! ::

    write_model_with_profile = .false.


      ! model_data_prefix
      ! ~~~~~~~~~~~~~~~~~

      ! prefix of the model data files

      ! ::

    model_data_prefix = 'profile'


      ! model_data_suffix
      ! ~~~~~~~~~~~~~~~~~

      ! suffix of the model data files

      ! ::

    model_data_suffix = '.mod'


      ! write_controls_info_with_profile
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if this is true, the values of the options in the controls
      ! inlist are written at same time as profiles

      ! ::

    write_controls_info_with_profile = .false.


      ! controls_data_prefix
      ! ~~~~~~~~~~~~~~~~~~~~

      ! prefix of the control data files

      ! ::

    controls_data_prefix = 'controls'


      ! controls_data_suffix
      ! ~~~~~~~~~~~~~~~~~~~~

      ! suffix of the control data files

      ! ::

    controls_data_suffix = '.data'


      ! mixing_D_limit_for_log
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! if max ``D_mix`` in mixing region is less than this, don't include the region in the log
      ! doesn't apply to thermohaline or semiconvective regions

      ! ::

    mixing_D_limit_for_log = 1d4


      ! write_pulse_data_with_profile
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If ``.true.``, also save model data in a format compatible with pulsation codes.

      ! ::

    write_pulse_data_with_profile = .false.


      ! pulse_data_format
      ! ~~~~~~~~~~~~~~~~~

      ! Format of pulsation data. Current options (case insensitive) are:

      ! ``'CAFEIN'``
      !   Format defined for CAFein (`Valsecchi et al. 2013 <https://ui.adsabs.harvard.edu/abs/2013ApJ...773...39V>`_).

      ! ``'FGONG'``
      !   Format originally defined for the GONG solar model project. A
      !   definition was given in 2005 for the `CoRoT/ESTA project`_ and
      !   `GONG itself <https://phys.au.dk/~jcd/solar_models/file-format.pdf>`_.
      !   MESA's implementation largely follows this subsequent
      !   `2015 definition <https://phys.au.dk/~jcd/ASTEC_results/file-format.pdf>`_.

      ! ``'OSC'``
      !   Format similar to FGONG originally produced for models from CESAM.
      !   Also defined for the `CoRoT/ESTA project`_.

      ! ``'GYRE'``
      !   The `plain-text format`_ defined for GYRE, which GYRE itself refers to as ``'MESA'`` format.

      ! ``'GSM'``
      !   The `HDF5-based format`_ defined for GYRE.

      ! ``'SAIO'``
      !   Format for Saio's pulsation code.

      ! ``'GR1D'``
      !   Format for GR1D, defined in Sec. 3 of the `GR1D documentation`_.

      ! .. _CoRoT/ESTA project: http://www.astro.up.pt/corot/ntools/docs/CoRoT_ESTA_Files.pdf
      ! .. _plain-text format: https://gyre.readthedocs.io/en/stable/ref-guide/stellar-models/mesa-file-format.html
      ! .. _HDF5-based format: https://gyre.readthedocs.io/en/stable/ref-guide/stellar-models/gsm-file-format.html
      ! .. _GR1D documentation: https://github.com/evanoconnor/GR1D/blob/v2.0/docs/README.pdf

      ! ::

    pulse_data_format = 'FGONG'


      ! add_atmosphere_to_pulse_data
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if true, write atmosphere to pulse files.
      ! This is not valid when ``atm_option = 'table'``

      ! ::

    add_atmosphere_to_pulse_data = .false.


      ! add_center_point_to_pulse_data
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if true, add point for r=0 to pulse files

      ! ::

    add_center_point_to_pulse_data = .true.


      ! keep_surface_point_for_pulse_data
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if true, add k=1 cell to pulse files

      ! ::

    keep_surface_point_for_pulse_data = .false.


      ! add_double_points_to_pulse_data
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! add double points at discontinuities

      ! ::

    add_double_points_to_pulse_data = .false.


      ! interpolate_rho_for_pulse_data
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, then get ``rho_face`` by interpolating rho at cell center.
      ! If false, then calculate rho_face by ``dm/(4*pi*r^2*dr)``.

      ! ::

    interpolate_rho_for_pulse_data = .true.


      ! threshold_grad_mu_for_double_point
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! threshold in grad_mu = dln(mu)/dln(P) for a double point to be written

      ! ::

    threshold_grad_mu_for_double_point = 10d0


      ! max_number_of_double_points
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! maximum number of double points to be written (0 = no limit); when this limit
      ! is set, double points are chosen in order of decreasing :math:`|\nabla_\mu|`

      ! ::

    max_number_of_double_points = 0


      ! fgong_header
      ! ~~~~~~~~~~~~
      !
      ! These are the four lines of arbitrary text that appear at the
      ! beginning of an FGONG file to describe its contents.

      ! ::

    fgong_header(1) = 'FGONG file'
    fgong_header(2) = 'Created by MESAstar'
    fgong_header(3) = ''
    fgong_header(4) = ''

      ! fgong_ivers
      ! ~~~~~~~~~~~
      !
      ! The version number for the FGONG file, which can only be 300 or 1300.
      ! 300 gives the old narrow format ``'(1P5E16.9,x)'``, which
      ! can produce numbers with no space separating them.
      ! 1300 gives the 'wide' FGONG format ``'(1P,5(X,E26.18E3))'``, as agreed on at the
      ! 5th Aarhus RGB workshop (University of Birmingham, UK, October 2015).

      ! ::

    fgong_ivers = 1300 ! 300 or 1300 only

      ! format_for_OSC_data
      ! ~~~~~~~~~~~~~~~~~~~

      ! float format for ``'OSC'`` data format

      ! ::

    format_for_OSC_data = '(1P5E19.12,x)'

      ! gyre_data_schema
      ! ~~~~~~~~~~~~~~~~

      ! data schema to use when passing model internally to GYRE, and/or
      ! writing files in GYRE/GSM format. For instance, to write v1.20 GYRE files
      ! use the value 120

      ! ::

    gyre_data_schema = 101

      ! max_num_gyre_points
      ! ~~~~~~~~~~~~~~~~~~~

      ! limit gyre output files to at most this number of points
      ! only used when > 1

      ! ::

    max_num_gyre_points = -1


      ! fgong_zero_A_inside_r
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! when writing FGONG, if r < this and cell has mixing of some kind, force A = 0
      ! Rsun units

      ! ::

    fgong_zero_A_inside_r = 0d0


      ! trace_mass_location
      ! ~~~~~~~~~~~~~~~~~~~

      ! location for ``trace_mass_radius``, ``trace_mass_logT``, etc. (Msun units)

      ! ::

    trace_mass_location = 0


      ! min_tau_for_max_abs_v_location
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! controls choice of location in model for ``max_abs_v`` history info.
      ! can use this to exclude locations too close to surface.
      ! ignore if <= 0

      ! ::

    min_tau_for_max_abs_v_location = 0


      ! min_q_for_inner_mach1_location
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! controls choice of location in model for innermost mach 1 history info.
      ! can use this to exclude locations too close to center.

      ! ::

    min_q_for_inner_mach1_location = 0


      ! max_q_for_outer_mach1_location
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! controls choice of location in model for outermost mach 1 history info.
      ! can use this to exclude locations too close to surface.

      ! ::

    max_q_for_outer_mach1_location = 1


      ! burn_min1
      ! ~~~~~~~~~

      ! used for reporting where burning zones occur, for example in the pgstar TRho profiles.
      ! see ``star/public/star_data.inc`` for details.
      ! must be < ``burn_min2``.
      ! In ergs/g/sec.

      ! ::

    burn_min1 = 50


      ! burn_min2
      ! ~~~~~~~~~

      ! used for reporting where burning zones occur, for example in the pgstar TRho profiles.
      ! see ``star/public/star_data.inc`` for details.
      ! In ergs/g/sec.

      ! ::

    burn_min2 = 1000


      ! width_for_limit_conv_vel
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! look this number of cells on either side of boundary to see if
      ! any boundary k in that range has s% csound(k) < s% v(k) <= s% csound(k-1)
      ! i.e. transition from subsonic to supersonic as go inward
      ! if find any such transition then don't allow increase in convection velocity.
      ! this implies no change from radiative to convective.
      ! the purpose of this is to prevent convective energy transport
      ! from moving energy from behind a shock to in front of the shock.

      ! ::

    width_for_limit_conv_vel = 3


      ! max_q_for_limit_conv_vel
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! for q(k) <= this, don't allow conv_vel to grow

      ! ::

    max_q_for_limit_conv_vel = -1


      ! max_r_in_cm_for_limit_conv_vel
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! for r(k) <= this, don't allow conv_vel to grow

      ! ::

    max_r_in_cm_for_limit_conv_vel = -1


      ! max_mass_in_gm_for_limit_conv_vel
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! for m(k) <= this, don't allow conv_vel to grow

      ! ::

    max_mass_in_gm_for_limit_conv_vel = -1


      ! center_avg_value_dq
      ! ~~~~~~~~~~~~~~~~~~~

      ! reported center values are averages over this fraction of star mass

      ! ::

    center_avg_value_dq = 1d-8


      ! surface_avg_abundance_dq
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! reported surface abundances are averages over this fraction of star mass

      ! ::

    surface_avg_abundance_dq = 1d-8


      ! conv_core_gap_dq_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! skip non-convective gaps of less than this limit when reporting convective core size

      ! ::

    conv_core_gap_dq_limit = 0d0

! definition of core boundaries
! =============================


      ! he_core_boundary_h1_fraction
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If fraction >= 0, boundary is outermost location where h1 mass fraction is <= this value,
      ! and he4 mass fraction >= ``min_boundary_fraction`` (see below).
      ! If fraction < 0, boundary is outermost location where he4 is the most abundant species.

      ! ::

    he_core_boundary_h1_fraction = 0.1d0


      ! co_core_boundary_he4_fraction
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If fraction >= 0, boundary is outermost location where he4 mass fraction is <= this value,
      ! and c12+o16 mass fraction >= ``min_boundary_fraction`` (see below).
      ! If fraction < 0, boundary is outermost location where c12+o16 is more abundant than any other species.

      ! ::

    co_core_boundary_he4_fraction = 0.1d0


      ! one_core_boundary_he4_c12_fraction
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If fraction >= 0, boundary is outermost location where combine he4+c12 mass fraction is <= this value,
      ! and o16+ne20 mass fraction >= ``min_boundary_fraction`` (see below).
      ! If fraction < 0, boundary is outermost location where o16+ne20 is more abundant than any other species.

      ! ::

    one_core_boundary_he4_c12_fraction = 0.1d0


      ! fe_core_boundary_si28_fraction
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! For this case, "iron" includes any species with A > 46.
      ! If fraction >= 0, boundary is outermost location where si28 mass fraction is <= this value,
      ! and "iron" mass fraction >= ``min_boundary_fraction`` (see below).
      ! If fraction < 0, boundary is outermost location where "iron" is the most abundant species.

      ! ::

    fe_core_boundary_si28_fraction = 0.1d0


      ! neutron_rich_core_boundary_Ye_max
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Boundary is outermost location where Ye is <= this value.

      ! ::

    neutron_rich_core_boundary_Ye_max = 0.48d0


      ! min_boundary_fraction
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Value for deciding boundary regions.

      ! ::

    min_boundary_fraction = 0.1d0

! when to stop
! ============


      ! max_model_number
      ! ~~~~~~~~~~~~~~~~

      ! The code will stop when it reaches this model number.
      ! Negative means no maximum.

      ! ::

    max_model_number = -1


      ! when_to_stop_rtol
      ! ~~~~~~~~~~~~~~~~~
      ! when_to_stop_atol
      ! ~~~~~~~~~~~~~~~~~

      ! Relative (``rtol``) and absolute (``atol``) error criteria for
      ! target stopping values.  To compare how accurately the last
      ! step satisfied a stopping condition, MESA evaluates ::

      !     error = abs(value - target_value)/ &
      !             (when_to_stop_atol + when_to_stop_rtol*max(abs(value), abs(target_value)))

      ! and will redo with a smaller timestep if ``error`` is greater
      ! than 1.  The default values ``1d99`` for both guarantee that
      ! ``error`` is tiny, so the run terminates as soon as a stopping
      ! condition is reached.

      ! If you wish to use either ``rtol`` or ``atol``, you should
      ! change the other to 0 (or your desired value).  To see why,
      ! suppose we only set ``when_to_stop_rtol = 1d-3``.  Because
      ! ``when_to_stop_atol`` is still ``1d99``, ``error`` will still
      ! be very small and MESA won't redo the last step.

      ! ::

    when_to_stop_rtol = 1d99
    when_to_stop_atol = 1d99


      ! max_age
      ! ~~~~~~~
      ! max_age_in_days
      ! ~~~~~~~~~~~~~~~
      ! max_age_in_seconds
      ! ~~~~~~~~~~~~~~~~~~

      ! Stop when the age of the star exceeds this value in years, days, or seconds.
      ! Only applies when > 0.

      ! ::

    max_age = 1d36
    max_age_in_days = -1
    max_age_in_seconds = -1


      ! num_adjusted_dt_steps_before_max_age
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! This adjusts ``max_years_for_timestep`` so that hit ``max_age`` exactly,
      ! without needing possibly large change in timestep at end of run.
      ! only used if > 0

      ! number of time steps to adjust to prior to hitting max age
      ! only used if > 0

      ! ::

    num_adjusted_dt_steps_before_max_age = 0


      ! dt_years_for_steps_before_max_age
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! timestep in years

      ! ::

    dt_years_for_steps_before_max_age = 1d6


      ! reduction_factor_for_max_timestep
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! per time step reduction limited to this

      ! ::

    reduction_factor_for_max_timestep = 0.98d0


      ! gamma_center_limit
      ! ~~~~~~~~~~~~~~~~~~

      ! gamma is the plasma interaction parameter.
      ! Stop when the center value of gamma exceeds this limit.

      ! ::

    gamma_center_limit = 1d99


      ! eta_center_limit
      ! ~~~~~~~~~~~~~~~~

      ! eta is the electron chemical potential in units of k*T.
      ! Stop when the center value of eta exceeds this limit.

      ! ::

    eta_center_limit = 1d99


      ! log_center_density_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! log_center_density_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Stop when log10 of the center density is above/below the upper/lower limit.

      ! ::

    log_center_density_upper_limit = 12d0
    log_center_density_lower_limit = -1d99


      ! log_center_temp_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! log_center_temp_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Stop when log10 of the center temperature is above/below the upper/lower limit.

      ! ::

    log_center_temp_upper_limit = 11d0
    log_center_temp_lower_limit = -1d99


      ! surface_accel_div_grav_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! This is used when do not have a velocity variable.
      ! The acceleration ratio is ``abs(accel)/grav`` at surface,
      ! where accel is ``(rdot-rdot_old)/dt`` and grav is ``G*m/r^2``.
      ! Stop if the ratio becomes larger than this limit.
      ! Ignored if <= 0.

      ! ::

    surface_accel_div_grav_limit = -1


      ! log_max_temp_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! log_max_temp_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when log10 of the maximum temperature is above/below the upper/lower limit.

      ! ::

    log_max_temp_upper_limit = 99
    log_max_temp_lower_limit = -99


      ! center_entropy_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! center_entropy_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when the center entropy is above/below the upper/lower limit.
      ! in kerg per baryon, where kerg = (erg K^-1)

      ! ::

    center_entropy_upper_limit = 1d99
    center_entropy_lower_limit = -1d99


      ! max_entropy_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! max_entropy_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when the max entropy is above/below the upper/lower limit.
      ! in kerg per baryon, where kerg = (erg K^-1)

      ! ::

    max_entropy_upper_limit = 1d99
    max_entropy_lower_limit = -1d99


      ! xa_central_lower_limit_species
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! xa_central_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Lower limits on central mass fractions.
      ! Stop when central abundance drops below this limit.
      ! Can have up to ``num_xa_central_limits`` of these (see ``star_def.inc`` for value).
      ! ``xa_central_lower_limit_species`` contains an isotope name as defined in ``chem_def.f90``.
      ! ``xa_central_lower_limit`` contains the lower limit value.

      ! ::

    xa_central_lower_limit_species(1) = ''
    xa_central_lower_limit(1) = 0


      ! xa_central_upper_limit_species
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! xa_central_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Upper limits on central mass fractions.
      ! Stop when central abundance rises above this limit.
      ! Can have up to ``num_xa_central_limits`` of these (see ``star_def.inc`` for value).
      ! E.g., to stop when center c12 abundance reaches 0.5, set

      ! ::

      !     xa_central_upper_limit_species(1) = 'c12'
      !     xa_central_upper_limit(1) = 0.5

      ! ::

    xa_central_upper_limit_species(1) = ''
    xa_central_upper_limit(1) = 0


      ! xa_surface_lower_limit_species
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! xa_surface_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Lower limits on surface mass fractions.
      ! Stop when surface abundance drops below this limit.
      ! Can have up to ``num_xa_surface_limits`` of these (see ``star_def`` for value)
      ! ``xa_surface_lower_limit_species`` contains an isotope name as defined in ``chem_def.f90``
      ! ``xa_surface_lower_limit`` contains the lower limit value

      ! ::

    xa_surface_lower_limit_species(1) = ''
    xa_surface_lower_limit(1) = 0


      ! xa_surface_upper_limit_species
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! xa_surface_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! upper limits on surface mass fractions
      ! stop when surface abundance rises above this limit
      ! can have up to ``num_xa_surface_limits`` of these (see ``star_def`` for value)
      ! e.g., to stop when surface c12 abundance reaches 0.5, set

      ! ::

      !     xa_surface_upper_limit_species(1) = 'c12'
      !     xa_surface_upper_limit(1) = 0.5

      ! ::

    xa_surface_upper_limit_species(1) = ''
    xa_surface_upper_limit(1) = 0


      ! xa_average_lower_limit_species
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! xa_average_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! lower limits on average mass fractions
      ! stop when average abundance drops below this limit
      ! can have up to ``num_xa_average_limits`` of these (see ``star_def`` for value)

      ! ::

    xa_average_lower_limit_species(1) = ''
    xa_average_lower_limit(1) = 0


      ! xa_average_upper_limit_species
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! xa_average_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! upper limits on average mass fractions
      ! stop when average abundance rises above this limit
      ! can have up to ``num_xa_average_limits`` of these (see ``star_def`` for value)

      ! ::

    xa_average_upper_limit_species(1) = ''
    xa_average_upper_limit(1) = 0


      ! HB_limit
      ! ~~~~~~~~

      ! For detecting when the model has completed the horizontal branch.
      ! Only applies when center abundance by mass of h1 is < 1d-4.
      ! Stop when the center abundance by mass of he4 drops below this limit.

      ! ::

    HB_limit = 0


      ! star_mass_min_limit
      ! ~~~~~~~~~~~~~~~~~~~

      ! Stop when star mass in Msun units is < this.  <= 0 means no limit.

      ! ::

    star_mass_min_limit = 0


      ! star_mass_max_limit
      ! ~~~~~~~~~~~~~~~~~~~

      ! Stop when star mass in Msun units is > this.  <= 0 means no limit.

      ! ::

    star_mass_max_limit = 0

      ! remnant_mass_min_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! ejecta_mass_max_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Stop when remnant mass in Msun units is < this.  <= 0 means no limit.
      ! remnant_mass = star_mass - ejecta_mass
      ! ejecta_mass is outermost mass that all has v(k) >= v_escape(k)

      ! ::

    remnant_mass_min_limit = 0
    ejecta_mass_max_limit = 1d99


      ! star_species_mass_min_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! star_species_mass_min_limit_iso
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! star_species_mass_max_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! star_species_mass_max_limit_iso
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Stop when a particular species mass in units of Msun exceeds these limits.

      ! ::

    star_species_mass_min_limit = 0
    star_species_mass_min_limit_iso = ''

      ! ::

    star_species_mass_max_limit = 0
    star_species_mass_max_limit_iso = ''


      ! star_H_mass_max_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Stop when star hydrogen mass in Msun units is > this.  <= 0 means no limit.

      ! star_H_mass_min_limit replaced by star_species_mass_min_limit
      ! star_He_mass_min_limit replaced by star_species_mass_min_limit
      ! star_C_mass_min_limit replaced by star_species_mass_min_limit
      ! star_H_mass_max_limit replaced by star_species_mass_max_limit
      ! star_He_mass_max_limit replaced by star_species_mass_max_limit
      ! star_C_mass_max_limit replaced by star_species_mass_max_limit


      ! envelope_mass_limit
      ! ~~~~~~~~~~~~~~~~~~~

      !     envelope_mass = star_mass - he_core_mass

      ! Stop when ``envelope_mass`` drops below this limit, in Msun units.

      ! ::

    envelope_mass_limit = 0


      ! envelope_fraction_left_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      !     envelope_fraction_left = (star_mass - he_core_mass)/(initial_mass - he_core_mass)

      ! Stop when ``envelope_fraction_left`` < this limit.

      ! ::

    envelope_fraction_left_limit = 0


      ! xmstar_min_limit
      ! ~~~~~~~~~~~~~~~~

      !     xmstar = mstar - M_center

      ! stop when xmstar in grams is < this.  <= 0 means no limit.

      ! ::

    xmstar_min_limit = 0


      ! xmstar_max_limit
      ! ~~~~~~~~~~~~~~~~

      !     xmstar = mstar - M_center

      ! stop when xmstar in grams is > this.  <= 0 means no limit.

      ! ::

    xmstar_max_limit = 0


      ! he_core_mass_limit
      ! ~~~~~~~~~~~~~~~~~~

      ! stop when helium core reaches this mass, in Msun units

      ! ::

    he_core_mass_limit = 1d99


      ! co_core_mass_limit
      ! ~~~~~~~~~~~~~~~~~~

      ! stop when CO core reaches this mass, in Msun units

      ! ::

    co_core_mass_limit = 1d99


      ! one_core_mass_limit
      ! ~~~~~~~~~~~~~~~~~~~

      ! stop when ONe core reaches this mass, in Msun units

      ! ::

    one_core_mass_limit = 1d99


      ! fe_core_mass_limit
      ! ~~~~~~~~~~~~~~~~~~

      ! stop when iron core reaches this mass, in Msun units

      ! ::

    fe_core_mass_limit = 1d99


      ! neutron_rich_core_mass_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when neutron rich core reaches this mass, in Msun units

      ! ::

    neutron_rich_core_mass_limit = 1d99


      ! he_layer_mass_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! he layer mass is defined as ``he_core_mass`` - ``c_core_mass``
      ! stop when ``c_core_mass`` > 0 and he layer mass < this limit (Msun units).

      ! ::

    he_layer_mass_lower_limit = 0


      ! abs_diff_lg_LH_lg_Ls_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when ``abs(lg_LH - lg_Ls) <= abs_diff_LH_Lsurf_limit``
      ! can be useful for deciding when pre-main sequence star has reached ZAMS
      ! set to negative value to disable

      ! ::

    abs_diff_lg_LH_lg_Ls_limit = -1


      ! Teff_upper_limit
      ! ~~~~~~~~~~~~~~~~

      ! stop when Teff is greater than this limit.

      ! ::

    Teff_upper_limit = 1d99


      ! Teff_lower_limit
      ! ~~~~~~~~~~~~~~~~

      ! stop when Teff is less than this limit.

      ! ::

    Teff_lower_limit = -1d99


      ! photosphere_r_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when ``photosphere_r`` is greater than this limit, in Rsun units

      ! ::

    photosphere_r_upper_limit = 1d99


      ! photosphere_r_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when ``photosphere_r`` is less than this limit, in Rsun units

      ! ::

    photosphere_r_lower_limit = -1d99


      ! photosphere_m_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when ``photosphere_m`` is greater than this limit, in Msun units

      ! ::

    photosphere_m_upper_limit = 1d99


      ! photosphere_m_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when ``photosphere_m`` is less than this limit, in Msun units

      ! ::

    photosphere_m_lower_limit = -1d99


      ! photosphere_m_sub_M_center_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when ``photosphere_m`` is less than this limit above ``M_center``, in Msun units

      ! ::

    photosphere_m_sub_M_center_limit = -1d99


      ! log_Teff_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! stop when log10 of Teff is greater than this limit.

      ! ::

    log_Teff_upper_limit = 1d99


      ! log_Teff_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! stop when log10 of Teff is less than this limit.

      ! ::

    log_Teff_lower_limit = -1d99


      ! log_Tsurf_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! stop when log10 of T in outermost cell is greater than this limit.

      ! ::

    log_Tsurf_upper_limit = 1d99


      ! log_Tsurf_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! stop when log10 of T in outermost cell is less than this limit.

      ! ::

    log_Tsurf_lower_limit = -1d99


      ! log_Rsurf_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! stop when log10 of R/Rsun in outermost cell is greater than this limit.

      ! ::

    log_Rsurf_upper_limit = 1d99


      ! log_Rsurf_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! stop when log10 of R/Rsun in outermost cell is less than this limit.

      ! ::

    log_Rsurf_lower_limit = -1d99


      ! log_L_upper_limit
      ! ~~~~~~~~~~~~~~~~~

      ! stop when log10(total luminosity in Lsun units) is greater than this limit.
      ! in order to skip pre-ms, this limit only applies when ``L_nuc`` > 0.01*L

      ! ::

    log_L_upper_limit = 1d99


      ! log_L_lower_limit
      ! ~~~~~~~~~~~~~~~~~

      ! stop when log10(total luminosity in Lsun units) is less than this limit.

      ! ::

    log_L_lower_limit = -1d99


      ! log_g_upper_limit
      ! ~~~~~~~~~~~~~~~~~

      ! stop when log10(gravity at surface) is greater than this limit.

      ! ::

    log_g_upper_limit = 1d99


      ! log_g_lower_limit
      ! ~~~~~~~~~~~~~~~~~

      ! stop when log10(gravity at surface) is less than this limit.

      ! ::

    log_g_lower_limit = -1d99


      ! log_Psurf_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! stop when log10 of surface pressure is greater than this limit.

      ! ::

    log_Psurf_upper_limit = 1d99


      ! log_Psurf_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! stop when log10 of surface pressure is less than this limit.

      ! ::

    log_Psurf_lower_limit = -1d99


      ! log_Dsurf_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! stop when log10 of surface density is greater than this limit.

      ! ::

    log_Dsurf_upper_limit = 1d99


      ! log_Dsurf_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! stop when log10 of surface density is less than this limit.

      ! ::

    log_Dsurf_lower_limit = -1d99


      ! power_nuc_burn_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when total power from all nuclear reactions (in Lsun units) is > this.

      ! ::

    power_nuc_burn_upper_limit = 1d99


      ! power_h_burn_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when total power from hydrogen-consuming reactions (in Lsun units) is > this.

      ! ::

    power_h_burn_upper_limit = 1d99


      ! power_he_burn_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when total power from reactions burning helium (in Lsun units) is > this.

      ! ::

    power_he_burn_upper_limit = 1d99


      ! power_z_burn_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when total power from reactions burning metals (in Lsun units) is > this

      ! ::

    power_z_burn_upper_limit = 1d99


      ! power_nuc_burn_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when total power from all nuclear reactions (in Lsun units) is < this.

      ! ::

    power_nuc_burn_lower_limit = -1d99


      ! power_h_burn_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when total power from hydrogen consuming reactions (in Lsun units) is < this.

      ! ::

    power_h_burn_lower_limit = -1d99


      ! power_he_burn_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when total power from reactions burning helium (in Lsun units) is < this.

      ! ::

    power_he_burn_lower_limit = -1d99


      ! power_z_burn_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop when total power from reactions burning metals (in Lsun units) is < this.

      ! ::

    power_z_burn_lower_limit = -1d99


      ! max_abs_rel_run_E_err
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Stop if the abs value of cumulative_energy_error/total_energy exceeds this value.
      ! Ignore if < 0. Also ignore during relax operations.

      ! ::

    max_abs_rel_run_E_err = -1


      ! max_number_retries
      ! ~~~~~~~~~~~~~~~~~~

      ! Stop if the number of retries exceeds this value.
      ! Ignore if < 0.

      ! ::

    max_number_retries = -1

      ! relax_max_number_retries
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! ::

    relax_max_number_retries = 300


      ! min_timestep_limit
      ! ~~~~~~~~~~~~~~~~~~

      ! stop if need timestep smaller than this limit, in seconds

      ! ::

    min_timestep_limit = 1d-6


      ! center_Ye_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! stop if ``center_ye`` drops below this limit

      ! ::

    center_Ye_lower_limit = -1


      ! center_R_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! stop if ``R_center`` drops below this limit (in cm)

      ! ::

    center_R_lower_limit = -1


      ! report_max_infall_inside_fe_core
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! use ``fe_core_infall_mass`` to check amount of mass that is collapsing.
      ! Then, If ``.true.``, fe_core_infall is determined by finding the maximum velocity that is inside
      ! ``fe_core_mass`` in units of Msun. if ``.false.``, report the maximum infall velocity at any location.

    report_max_infall_inside_fe_core = .true.

      ! fe_core_infall_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! stop if at least ``fe_core_infall_mass`` of material has speed greater than this, at a location interior to ``fe_core_mass``, in cm/s

      ! ::

    fe_core_infall_limit = 3d7

      ! fe_core_infall_mass
      ! ~~~~~~~~~~~~~~~~~~~

      ! if ``check_mass_sum_for_infall = .true.``, ``fe_core_infall_mass`` is the amount of mass to check if collapsing, the smaller this is the closer the velocity minima will be to ``fe_core_infall`` but there will be a greater chance of a
      ! transistent velocity spike causing the model to prematurely exit. In solar masses


    fe_core_infall_mass = 0.1d0


      ! non_fe_core_infall_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop if at least ``non_fe_core_infall_mass`` of material has speed greater than this, at a location interior to ``he_core_mass`` and exterior to ``fe_core_mass``. in cm/s

      ! ::

    non_fe_core_infall_limit = 1d99

      ! non_fe_core_infall_mass
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Amount of mass to check if collapsing, the smaller this is the closer the velocity minima will be to ``non_fe_core_infall`` but there will be a greater chance of a
      ! transistent velocity spike causing the model to prematurely exit. In solar masses


      non_fe_core_infall_mass = 0.1d0


      ! non_fe_core_rebound_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop if max rebound speed (outward) at any location interior to ``he_core_mass``. in cm/s

      ! ::

    non_fe_core_rebound_limit = 1d99


      ! v_div_csound_max_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! stop if any ``v/csound`` > this limit

      ! ::

    v_div_csound_max_limit = 1d99


      ! v_div_csound_surf_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! stop if ``v_surf/csound_surf`` > this limit

      ! ::

    v_div_csound_surf_limit = 1d99


      ! v_surf_div_v_kh_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop if ``abs(v_surf/v_kh)`` > this limit, where ``v_kh = photosphere_r/kh_timescale``

      ! ::

    v_surf_div_v_kh_upper_limit = 1d99


      ! v_surf_div_v_kh_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop if ``abs(v_surf/v_kh)`` < this limit, where ``v_kh = photosphere_r/kh_timescale``

      ! ::

    v_surf_div_v_kh_lower_limit = -1d99


      ! v_surf_div_v_esc_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! stop if ``v_surf/v_esc`` > this limit

      ! ::

    v_surf_div_v_esc_limit = 1d99


      ! v_surf_kms_limit
      ! ~~~~~~~~~~~~~~~~

      ! stop if ``v_surf`` in km/s > this limit

      ! ::

    v_surf_kms_limit = 1d99


      ! Lnuc_div_L_zams_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! defines "near zams" -- note: must also set ``stop_near_zams``

      ! ::

    Lnuc_div_L_zams_limit = 0.9d0


      ! stop_near_zams
      ! ~~~~~~~~~~~~~~

      ! if true, stop if Lnuc/L > ``Lnuc_div_L_zams_limit``

      ! ::

    stop_near_zams = .false.


      ! stop_at_phase_PreMS
      ! ~~~~~~~~~~~~~~~~~~~
      ! stop_at_phase_ZAMS
      ! ~~~~~~~~~~~~~~~~~~
      ! stop_at_phase_IAMS
      ! ~~~~~~~~~~~~~~~~~~
      ! stop_at_phase_TAMS
      ! ~~~~~~~~~~~~~~~~~~
      ! stop_at_phase_He_Burn
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! stop_at_phase_ZACHeB
      ! ~~~~~~~~~~~~~~~~~~~~
      ! stop_at_phase_TACHeB
      ! ~~~~~~~~~~~~~~~~~~~~
      ! stop_at_phase_TP_AGB
      ! ~~~~~~~~~~~~~~~~~~~~
      ! stop_at_phase_C_Burn
      ! ~~~~~~~~~~~~~~~~~~~~
      ! stop_at_phase_Ne_Burn
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! stop_at_phase_O_Burn
      ! ~~~~~~~~~~~~~~~~~~~~
      ! stop_at_phase_Si_Burn
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! stop_at_phase_WDCS
      ! ~~~~~~~~~~~~~~~~~~

      ! if true, terminate model when phase of evolution reaches this point.
      ! Definitions for stop_at_phase_* can be found in
      ! $MESA_DIR/star/private/star_utils.f90 inside the
      ! subroutine ``set_phase_of_evolution``

      ! ::

    stop_at_phase_PreMS = .false.
    stop_at_phase_ZAMS = .false.
    stop_at_phase_IAMS = .false.
    stop_at_phase_TAMS = .false.
    stop_at_phase_He_Burn = .false.
    stop_at_phase_ZACHeB = .false.
    stop_at_phase_TACHeB = .false.
    stop_at_phase_TP_AGB = .false.
    stop_at_phase_C_Burn = .false.
    stop_at_phase_Ne_Burn = .false.
    stop_at_phase_O_Burn = .false.
    stop_at_phase_Si_Burn = .false.
    stop_at_phase_WDCS = .false.


      ! Lnuc_div_L_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! stop when Lnuc/L is greater than this limit.
      ! Here, Lnuc refers to the total thermal power from all burning, including photodisintegrations,
      ! ``power_nuc_burn`` in the history_columns.list file.
      ! L is the luminosity at the photosphere.

      ! ::

    Lnuc_div_L_upper_limit = 1d99


      ! Lnuc_div_L_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! stop when Lnuc/L is less than this limit.
      ! Here, Lnuc refers to the total thermal power from all burning, including photodisintegrations,
      ! ``power_nuc_burn`` in the history_columns.list file.
      ! L is the luminosity at the photosphere.

      ! ::

    Lnuc_div_L_lower_limit = -1d99


      ! gamma1_limit
      ! ~~~~~~~~~~~~

      ! stop if min gamma1 < this limit in a cell with ``q <= gamma1_limit_max_q``

      ! ::

    gamma1_limit = -1


      ! gamma1_limit_max_q
      ! ~~~~~~~~~~~~~~~~~~

      ! stop if gamma1 < this limit at any location with ``q <= gamma1_limit_max_q``
      ! values near unity skip the outer envelope

      ! ::

    gamma1_limit_max_q = 0.95d0


      ! gamma1_limit_max_v_div_vesc
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop if gamma1 < this limit at any location with ``v_div_vesc <= gamma1_limit_max_v_div_vesc``

      ! ::

    gamma1_limit_max_v_div_vesc = 0.95d0


      ! Pgas_div_P_limit
      ! ~~~~~~~~~~~~~~~~

      ! stop when Pgas/P <= Pgas_div_P_limit

      ! ::

    Pgas_div_P_limit = 0


      ! Pgas_div_P_limit_max_q
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! stop if Pgas/P < Pgas_div_P_limit at any location with ``q <= Pgas_div_P_limit_max_q``
      ! values near unity skip the outer envelope

      ! ::

    Pgas_div_P_limit_max_q = 0.95d0


      ! peak_burn_vconv_div_cs_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! limits ratio of convection velocity to sound speed at location of peak ``eps_nuc``

      ! ::

    peak_burn_vconv_div_cs_limit = 1d99


      ! omega_div_omega_crit_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! stop if omega/omega_crit is > this anywhere in star
      ! ignore if < 0

      ! ::

    omega_div_omega_crit_limit = -1


      ! delta_nu_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! stop when asteroseismology ``delta_nu`` in micro Hz is < this.  <= 0 means no limit.

      ! ::

    delta_nu_lower_limit = 0


      ! delta_nu_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! stop when asteroseismology ``delta_nu`` in micro Hz is > this.  <= 0 means no limit.

      ! ::

    delta_nu_upper_limit = 0


      ! shock_mass_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! stop when shock_mass is > this.  <= 0 means no limit.

      ! ::

    shock_mass_upper_limit = -1


      ! mach1_mass_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! stop when outer location of mach 1 is > this.  <= 0 means no limit.

      ! ::

    mach1_mass_upper_limit = -1


      ! delta_Pg_lower_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! stop when ``delta_Pg`` in micro Hz is < this.  <= 0 means no limit.

      ! ::

    delta_Pg_lower_limit = 0


      ! delta_Pg_upper_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! stop when ``delta_Pg`` in micro Hz is > this.  <= 0 means no limit.

      ! ::

    delta_Pg_upper_limit = 0


      ! stop_when_reach_this_cumulative_extra_heating
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! (ignore if <= 0)

      ! ::

    stop_when_reach_this_cumulative_extra_heating = 0d0

! mixing parameters
! =================


      ! mixing_length_alpha
      ! ~~~~~~~~~~~~~~~~~~~

      ! The mixing length is this parameter times a local pressure scale height.
      ! To increase R vs. L, decrease ``mixing_length_alpha``.

      ! ::

    mixing_length_alpha = 2


      ! remove_small_D_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If MLT diffusion coeff D (cm^2/sec) is less than this limit,
      ! then set D to zero and change the point to ``mixing_type == no_mixing``.

      ! ::

    remove_small_D_limit = 1d-6


      ! use_Ledoux_criterion
      ! ~~~~~~~~~~~~~~~~~~~~

      ! a location in the model is Schwarzschild stable when ``gradr < grada``
      ! it is Ledoux stable when ``gradr < gradL``, where ``gradL = grada + composition_gradient``
      ! note that these are the same when ``composition_gradient = 0``
      ! so you can force the use of the Schwarzschild criterion by passing 0 for
      ! the ``composition_gradient`` argument to the mlt routine.
      ! that's what happens if you set the control "``use_Ledoux_criterion``" to false.

      ! overshooting and rotational mixing are dealt with separately
      !  and are added after the MLT classifications are made.

      ! ::

    use_Ledoux_criterion = .false.


      ! num_cells_for_smooth_gradL_composition_term
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Number of cells on either side to use in weighted smoothing of ``gradL_composition_term``.
      ! ``gradL_composition_term`` is set to the "raw" unsmoothed ``brunt_B``
      ! and then optionally smoothed according ``num_cells_for_smooth_gradL_composition_term``.
      ! In cases where the Ledoux criterion is used to evaluate the boundary for burning
      ! convective cores, you may need to set ``num_cells_for_smooth_gradL_composition_term = 0``
      ! to avoid smoothing the stabilizing composition jump into the convection zone and
      ! unphysically causing it to shrink. See section 3.2 in Moore, K., & Garaud, P. 2016, APJ, 817, 54

      ! ::

    num_cells_for_smooth_gradL_composition_term = 3


      ! threshold_for_smooth_gradL_composition_term
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Threshold for weighted smoothing of ``gradL_composition_term``. Only apply smoothing (controlled
      ! by ``num_cells_for_smooth_gradL_composition_term``) for contiguous regions where :math:`|\nabla_L|` exceeds
      ! this threshold. Might be useful for preventing narrow composition jumps from being excessively
      ! broadened by smoothing

      ! ::

    threshold_for_smooth_gradL_composition_term = 0


      ! alpha_semiconvection
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Determines efficiency of semiconvective mixing.
      ! Semiconvection only applies if ``use_Ledoux_criterion`` is true.

      ! ::

    alpha_semiconvection = 0

      ! semiconvection_option
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! + ``'Langer_85 mixing; gradT = gradr'`` : uses Langer scheme for mixing but sets gradT = gradr
      ! + ``'Langer_85'`` : this calculates special gradT as well as doing mixing.

      ! ::

    semiconvection_option = 'Langer_85 mixing; gradT = gradr'


      ! thermohaline_coeff
      ! ~~~~~~~~~~~~~~~~~~

      ! Determines efficiency of thermohaline mixing.
      ! was previously named ``thermo_haline_coeff``.
      ! thermohaline mixing only applies if ``use_Ledoux_criterion`` is true.

      ! ::

    thermohaline_coeff = 0


      ! thermohaline_option
      ! ~~~~~~~~~~~~~~~~~~~

      ! determines which method to use for calculating thermohaline diffusion coef:

      ! + ``'Kippenhahn'`` : use method of Kippenhahn, R., Ruschenplatt, G., & Thomas, H.-C. 1980, A&A, 91, 175.
      ! + ``'Traxler_Garaud_Stellmach_11'`` : use method of Traxler, Garaud, & Stellmach, ApJ Letters, 728:L29 (2011).
      ! + ``'Brown_Garaud_Stellmach_13'`` : use method of Brown, Garaud, & Stellmach, ApJ 768:34 (2013)
      !   Recommends ``thermohaline_coeff = 1``, but it can nevertheless be changed.

      ! ::

    thermohaline_option = 'Kippenhahn'


      ! alt_scale_height_flag
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! If false, then stick to the usual definition -- P/(g*rho).
      ! If true, use min of the usual and sound speed * hydro time scale, sqrt(P/G)/rho.
      ! Note that the 'TDC' ``MLT_option`` does not respect the ``alt_scale_height`` option, and continues to use ``h = P / rho g``
      ! even if that flag is set.

      ! ::

    alt_scale_height_flag = .true.


      ! mlt_use_rotation_correction
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! When doing rotation, multiply ``grad_rad`` by ``ft_rot/fp_rot`` if this flag is true.

      ! ::

    mlt_use_rotation_correction = .true.


      ! mlt_Pturb_factor
      ! ~~~~~~~~~~~~~~~~

      ! For MESA's momentum equation, include MLT turbulent pressure at face k = mlt_Pturb_factor*(1/3d0)*0.5*(rho(k) + rho(k-1))*mlt_vc(k)**2/3
      ! MLT turbulent pressure for cell k = avg of values at faces. For TDC, mlt_Pturb_factor = 2d0
      ! corresponds to TDC_alpha_Pt = 1d0, where Pt = (2/3)*rho(k)*(mlt_vc(k)/sqrt(2/3))**2

      ! this replaces conv_dP_term_factor.   also see extra_pressure vector and other_pressure routine

      ! ::

    mlt_Pturb_factor = 0d0


      ! MLT_option
      ! ~~~~~~~~~~

      ! Options are:

      ! + 'none'       : just give radiative values with no mixing.
      ! + 'TDC'        : Time-dependent convection based on the Khufuss 1986 model. Reduces to Cox at long times.
      ! + 'Cox'        : MLT as developed in Cox & Giuli 1968, Chapter 14.
      ! + 'ML1'        : Bohm-Vitense 1958
      ! + 'ML2'        : Bohm and Cassinelli 1971
      ! + 'Mihalas'    : Mihalas 1978, Kurucz 1979
      ! + 'Henyey'     : Henyey, Vardya, and Bodenheimer 1965

      ! The 'Cox' and 'TDC' options assumes optically thick material.
      ! The other options are various ways of extending to include optically thin material.
      ! Note that TDC does not respect the ``alt_scale_height`` option, and continues to use ``h = P / rho g``
      ! even if that flag is set.

      ! We caution that combining different mixing models in a stellar evolution
      ! calculation might lead to physically inconsistent solutions,
      ! because the different models have been developed separately,
      ! and their underlying assumptions might not be compatible with each other.
      ! Examples include combining the newly implemented time-dependent local limit
      ! convection model ``TDC`` with an overshooting model, or combining ``TDC``
      ! with other models for chemical composition gradients
      ! (predictive mixing or convective premixing), rotation, etc. (MESA VI)

      ! ::

    MLT_option = 'TDC'

      ! TDC options
      ! ~~~~~~~~~~~
      ! + ``TDC_alpha_D``  : The turbulent viscous damping parameter which determines the saturation of TDC. Increasing this decreases convection speeds. This control is analogous to RSP_alfad, and previously called alpha_TDC_DAMP.
      ! + ``TDC_alpha_R``  : The radiative damping parameter which determines the saturation of TDC. Increasing this decreases convection speeds. This control is analogous to RSP_gammar, and previously called alpha_TDC_DAMPR.
      ! + ``TDC_alpha_Pt`` : The prefactor on the term accounting for work done against turbulent pressure (P_turb * dV/dt). Physically this should be unity. Turbulent pressure effects on the momentum equations are set by ``mlt_Pturb_factor``. Together, These controls are analogous to RSP_alfap, and previously called alpha_TDC_PtdVdt.
      ! + ``TDC_alpha_M``  : The prefactor on the term accounting for eddy viscous dissipation. This control is analogous to RSP_alfam.
      ! + ``TDC_alpha_C``  : The prefactor on the convective flux. This control is analogous to RSP_alfac.
      ! + ``TDC_alpha_S``  : The prefactor on the convective source term, S . This control is analogous to RSP_alfas.

      ! + ``steps_before_use_TDC`` : TDC often struggles with models on the pre-main-sequence. Set this option to pick MLT_option='Cox' for the first several steps to get past the pre-MS. Note that if this option is positive then only either TDC or Cox will be used (depending on model number). THIS OVERRIDES MLT_option!

      ! ::

     TDC_alpha_D = 1d0
     TDC_alpha_R = 0d0
     TDC_alpha_Pt = 0d0
     TDC_alpha_C = 1d0
     TDC_alpha_S = 1d0
     steps_before_use_TDC = 0


      ! If ``TDC_alpha_M > 0``, then include eddy viscous damping in TDC ``TDC_alpha_M``
      ! This control is analogous to ``RSP_alfam``, where the default is ``RSP_alfam = 0.25d0``.

      ! If hydrostatic (``v_flag = .false.```, ``u_flag = .false.``, v = 0) there will be no velocity gradients,
      ! and thus no shear to drive turbulence, hence the eddy viscosity term will become zero.
      ! Details on the implementation of ``TDC_alpha_M`` can be found in `Farag et al. (2026) <https://arxiv.org/abs/2603.15766>`_

      ! ::

     TDC_alpha_M = 0d0


      ! TDC_alpha_M_use_explicit_mlt_vc_in_momentum_equation
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if ``TDC_alpha_M_use_explicit_mlt_vc_in_momentum_equation = .true.``, mlt_vc_old (the start of step value)
      ! is used in place of the current solver iterate mlt_vc_ad inside the hydro momentum equation. This option can
      ! provide greater numerical stability in extremely dynamic models.

      ! ::

     TDC_alpha_M_use_explicit_mlt_vc_in_momentum_equation = .false.


      ! include_mlt_corr_to_TDC
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! If include_mlt_corr_to_TDC = .true. , mlt correction to TDC follows MESA VI (Jermyn et a. 2023)
      ! in which we correct TDC on long timescales with Y_face ~ Y*Gamma/(1+Gamma). If .false., abandon
      ! mlt limit of tdc and adopt original form of (Kuhfuß 1986) convection model in the local limit.

      ! ::

     include_mlt_corr_to_TDC = .true.

      ! TDC_include_eturb_in_energy_equation
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! While ``TDC`` is already implicitly coupled to the total energy equation, this
      ! controls feedsback the turbulent energy into the total energy equation by
      ! calculating and incorporating det/dt from TDC as a source term in
      ! the total energy equation, along with the eddy viscous heating Eq. This comes
      ! at the cost of numerical stability on long timescales, be warned.

      ! ::

     TDC_include_eturb_in_energy_equation = .false.


      ! use_rsp_form_of_scale_height
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Calculate scale height by averaging P/rho onto faces together instead
      ! of of wrapping P and rho separately by default. Both forms assume HSE.
      ! Not compatible with alt_scale_height_flag.

      ! ::

     use_rsp_form_of_scale_height = .false.


      ! TDC_num_innermost_cells_forced_nonturbulent
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! TDC_num_outermost_cells_forced_nonturbulent
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Forces innermost TDC_num_innermost_cells_forced_nonturbulent or
      ! TDC_num_outermost_cells_forced_nonturbulent cells
      ! to be nonturbulent, and sets gradT = gradr in these cells.
      ! Useful for pulsation models in TDC. This control
      ! supports all mlt options as well.

      ! ::

     TDC_num_innermost_cells_forced_nonturbulent = 0
     TDC_num_outermost_cells_forced_nonturbulent = 0


      ! Henyey_MLT_y_param
      ! ~~~~~~~~~~~~~~~~~~
      ! Henyey_MLT_nu_param
      ! ~~~~~~~~~~~~~~~~~~~

      ! Values of the f1..f4 coefficients are taken from Table 1 of `Ludwig et al. (1999) <https://ui.adsabs.harvard.edu/abs/1999A%26A...346..111L>`_
      ! with the following exception: their value of f3 for Henyey convection is ``f4/8`` when it should be
      ! ``8*f4``, i.e., ``f3=32*pi**2/3`` and ``f4=4*pi**2/3``. f3 and f4 are related to the henyey y parameter, so
      ! for the 'Henyey' case they are set based on the value of ``Henyey_y_param``.

      ! ::

    Henyey_MLT_y_param = 0.33333333d0
    Henyey_MLT_nu_param = 8


      ! make_gradr_sticky_in_solver_iters
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_logT_for_make_gradr_sticky_in_solver_iters
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if true, then location that becomes radiative during solver iterations,
      ! stays radiative for rest of the solver iterations.
      ! to avoid flip-flopping between radiative and convective.
      ! also do this if max logT >= min_logT_for_make_gradr_sticky_in_solver_iters

      ! ::

    make_gradr_sticky_in_solver_iters = .false.
    min_logT_for_make_gradr_sticky_in_solver_iters = 1d99


      ! no_MLT_below_shock
      ! ~~~~~~~~~~~~~~~~~~

      ! if true, then no MLT below an outward going shock (just radiative).

      ! ::

    no_MLT_below_shock = .false.


      ! mlt_make_surface_no_mixing
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    mlt_make_surface_no_mixing = .false.


      ! T_mix_limit
      ! ~~~~~~~~~~~

      ! If there is any convection in surface zones with ``T < T_mix_limit``,
      ! then extend the innermost such convective region outward all the way to the surface.
      ! For example,

      ! + ``T_mix_limit <= 0`` means omit this operation.
      ! + ``T_mix_limit = 1d5`` will effectively make the star convective down to the He++ region.

      ! units in Kelvin

      ! ::

    T_mix_limit = 0


      ! mlt_gradT_fraction
      ! ~~~~~~~~~~~~~~~~~~

      ! let f := ``mlt_gradT_fraction``
      ! if f is >= 0 and <= 1, then
      ! gradT from mlt is replaced by ``f*grada_at_face(k) + (1-f)*gradr(k)``
      ! see also the vector control ``adjust_mlt_gradT_fraction`` for fine grain control

      ! ::

    mlt_gradT_fraction = -1


      ! okay_to_reduce_gradT_excess
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ``gradT_excess`` = ``gradT_sub_grada`` = superadiabaticity.

      ! Inefficient convection => large gradT excess and steep T gradient to enhance radiative transport.
      ! Reduce gradT excess by making gradT closer to adiabatic gradient.
      ! If true, code is allowed to adjust gradT to boost efficiency of energy transport
      ! See ``gradT_excess_f1``, ``gradT_excess_f2``, and ``gradT_excess_age_fraction`` below.

      ! This is the treatment of convection, referred to as MLT++
      ! in Section 7.2 of Paxton et al. (2013), that reduces the
      ! superadiabaticity in some radiation-dominated convective regions.

      ! ::

    okay_to_reduce_gradT_excess = .false.


      ! gradT_excess_f1
      ! ~~~~~~~~~~~~~~~
      ! gradT_excess_f2
      ! ~~~~~~~~~~~~~~~

      ! These are for calculation of efficiency boosted gradT.

      ! ::

    gradT_excess_f1 = 1d-4
    gradT_excess_f2 = 1d-3


      ! gradT_excess_age_fraction
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! These are for calculation of efficiency boosted gradT.
      ! Fraction of old to mix with new to get next.

      ! ::

    gradT_excess_age_fraction = 0.9d0


      ! gradT_excess_max_change
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! These are for calculation of efficiency boosted gradT.
      ! Maximum change allowed in one timestep for ``gradT_excess_alpha``.
      ! Ignored if negative.

      ! ::

    gradT_excess_max_change = -1d0


      ! gradT_excess_lambda1
      ! ~~~~~~~~~~~~~~~~~~~~
      ! gradT_excess_beta1
      ! ~~~~~~~~~~~~~~~~~~

      ! In some situations you might want to force alfa = 1.
      ! You can do that by setting ``gradT_excess_lambda1 < 0``.
      ! The following are for the normal calculation of ``gradT_excess_alfa``

      ! ::

    gradT_excess_lambda1 = 1.0d0
    gradT_excess_beta1 = 0.35d0


      ! gradT_excess_lambda2
      ! ~~~~~~~~~~~~~~~~~~~~
      ! gradT_excess_beta2
      ! ~~~~~~~~~~~~~~~~~~

      ! The following are for the normal calculation of ``gradT_excess_alfa``.

      ! ::

    gradT_excess_lambda2 = 0.5d0
    gradT_excess_beta2 = 0.25d0


      ! gradT_excess_dlambda
      ! ~~~~~~~~~~~~~~~~~~~~
      ! gradT_excess_dbeta
      ! ~~~~~~~~~~~~~~~~~~

      ! The following are for the normal calculation of ``gradT_excess_alfa``.

      ! ::

    gradT_excess_dlambda = 0.1d0
    gradT_excess_dbeta = 0.1d0


      ! gradT_excess_max_center_h1
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! No boost if center H1 > this limit.

      ! ::

    gradT_excess_max_center_h1 = 1d0


      ! gradT_excess_min_center_he4
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! No boost if center He4 < this limit.

      ! ::

    gradT_excess_min_center_he4 = 0d0


      ! gradT_excess_max_logT
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! No local boost if local logT > this limit.

      ! ::

    gradT_excess_max_logT = 8


      ! gradT_excess_min_log_tau_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! gradT_excess_max_log_tau_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! No local boost if local ``log_tau < gradT_excess_max_log_tau_full_off``.
      ! Reduced local boost if local ``log_tau < gradT_excess_min_log_tau_full_on``.

      ! ::

    gradT_excess_min_log_tau_full_on = -99
    gradT_excess_max_log_tau_full_off = -99


      ! max_logT_for_mlt
      ! ~~~~~~~~~~~~~~~~

      ! No MLT at cell if local logT > this limit.

      max_logT_for_mlt = 99

      ! use_superad_reduction
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! superad_reduction_Gamma_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! superad_reduction_Gamma_limit_scale
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! superad_reduction_Gamma_inv_scale
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! superad_reduction_diff_grads_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! superad_reduction_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Implicit alternative to ``okay_to_reduce_gradT_excess``

      ! ::

      use_superad_reduction = .false.
      superad_reduction_Gamma_limit = 0.5d0
      superad_reduction_Gamma_limit_scale = 5d0
      superad_reduction_Gamma_inv_scale = 5d0
      superad_reduction_diff_grads_limit = 1d-3
      superad_reduction_limit = -1d0


   ! overshooting
   ! ____________

      ! There are three schemes implemented in MESA to treat overshooting:
      ! a step overshoot scheme, an exponential scheme, and a step+exponential scheme.

      ! Parameters for exponential diffusive overshoot are described in the paper by Falk Herwig,
      ! "The evolution of AGB stars with convective overshoot", A&A, 360, 952-968 (2000).

      ! Overshooting depends on the classification of the convective zone and can be different at the top and the bottom of the zone.

      ! The overshooting controls are based on convection-zone and convection-boundary matching criteria.
      ! These criteria are ``overshoot_zone_type``, ``overshoot_zone_loc`` and ``overshoot_bdy_loc``.
      ! The overshooting parameter values corresponding to the first set of matching criteria will be used.
      ! Therefore, narrower criteria should precede more general ones (i.e have lower array indices).

      ! These are arrays of size ``NUM_OVERSHOOT_PARAM_SETS`` which is defined in
      ! ``star_data/public/star_data_def.inc`` (currently 16)

      ! ::

    overshoot_scheme(:) = '' ! ``exponential``, ``step``, ``step+exponential``, ``other``
    overshoot_zone_type(:) = '' !  ``burn_H``, ``burn_He``, ``burn_Z``, ``nonburn``, ``any``
    overshoot_zone_loc(:) = '' ! ``core``, ``shell``, ``any``
    overshoot_bdy_loc(:) = '' ! ``bottom``, ``top``, ``any``

      ! Amount of overshooting from edge of convective zone
      ! These are arrays of size ``NUM_OVERSHOOT_PARAM_SETS`` which is defined in
      ! ``star_data/public/star_data_def.inc`` (currently 16)

      ! ::

    overshoot_f(:) = 0d0
    overshoot_f2(:) = 0d0
    overshoot_f0(:) = 0d0

      ! The switch from convective mixing to overshooting happens at a distance f0*Hp into the convection zone
      ! from the estimated location where ``grad_ad = grad_rad``, where Hp is the pressure scale height at that location.
      ! A value <= 0 for f0 is a mistake -- you are required to set f0 as well as f (and f2 if using step+exponential).
      ! take a look at the following from an email concerning this:
      ! Overshooting works by taking the diffusion mixing coefficient at the edge
      ! of the convection zone and extending it beyond the zone. But -- and here's the issue --
      ! at the exact edge of the zone the mixing coefficient goes to 0. So we don't want that.
      ! Instead we want the value of the mixing coeff NEAR the edge, but not AT the edge.
      ! The "f0" parameter determines the exact meaning of "near" for this. It tells the code
      ! how far back into the zone to go in terms of scale height. The overshooting actually
      ! begins at the location determined by f0 back into the convection zone rather than at
      ! the edge where the diffusion coeff is ill-defined. So, for example, if you want
      ! overshooting of 0.2 scale heights beyond the normal edge, you might want to back up
      ! 0.05 scale heights to get the diffusion coeff from near the edge and then go out
      ! by 0.25 scale heights from there to reach 0.2 Hp beyond the old boundary. In the
      ! inlist this would mean setting the "f0" to 0.05 and the "f" to 0.25.

      ! For step overshoot: overshooting extends a distance overshoot_f*Hp0 from r0 with constant diffusion coefficient
      ! D = overshoot_D0 + overshoot_Delta0*D_ob
      ! where D_ob is the convective diffusivity at the bottom (top) of the step overshoot region for outward (inward) overshooting.
      ! These are arrays of size ``NUM_OVERSHOOT_PARAM_SETS`` which is defined in
      ! ``star_data/public/star_data_def.inc`` (currently 16)

      ! If you use the 'step+exponential' scheme, the step is placed first and the
      ! exponential component follows it. In this scheme, ``overshoot_f`` sets
      ! the width of the step part and ``overshoot_f2`` sets the length scale of
      ! the additional exponential tail. The parameterizations for both parts are
      ! still evaluated at the convective boundary (as described above); the
      ! exponential part is displaced by the extent of the step part.
      ! This approach is motivated by:
      ! Michielsen et al. 2021 (`A&A 650, A175 <https://doi.org/10.1051/0004-6361/202039926>`_)
      ! Anders et al. 2022a (`ApJ 926, 169 <https://doi.org/10.3847/1538-4357/ac408d>`_)
      ! Anders et al. 2022b (`ApJL 928, L10 <https://doi.org/10.3847/2041-8213/ac5cb5>`_)
      ! Johnston et al. 2024 (`ApJ 964, 170 <https://doi.org/10.3847/1538-4357/ad2343>`_)

      ! The step overshoot part models convective entrainment, where a convective
      ! zone "eats up" a Ledoux-stable region (typically above a convective core).
      ! The exponential overshoot part then models actual overshooting where inertia
      ! carries material beyond the Schwarzschild boundary.
      ! Note however that no temperature gradients are modified, MESA's implementation of overshoot
      ! only extends mixing regions (through the diffusion coefficients, ``D_mix``)

      ! ::

    overshoot_D0(:) = 0d0
    overshoot_Delta0(:) = 1d0

      ! You can specify a range of star masses over which overshooting
      ! above H burning zones is gradually enabled.
      ! Do specified overshooting above H burning zone if ``star_mass`` >= this (Msun).
      ! These are arrays of size ``NUM_OVERSHOOT_PARAM_SETS`` which is defined in
      ! ``star_data/public/star_data_def.inc`` (currently 16)

      ! ::

    overshoot_mass_full_on(:) = 0d0

      ! You can specify a range of star masses over which overshooting
      ! above H burning zones is gradually enabled.
      ! No overshooting above H burning zone if ``star_mass`` <= this  (Msun).
      ! These are arrays of size ``NUM_OVERSHOOT_PARAM_SETS`` which is defined in
      ! ``star_data/public/star_data_def.inc`` (currently 16)

      ! ::

    overshoot_mass_full_off(:) = 0d0


      ! overshoot_D_min
      ! ~~~~~~~~~~~~~~~

      ! Overshooting shuts off when the exponential decay has dropped the diffusion
      ! coefficient to this level.

      ! ::

    overshoot_D_min = 1d-2


      ! overshoot_brunt_B_max
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Terminate overshoot region when encounter stabilizing composition gradient
      ! where (unsmoothed) ``brunt_B`` is greater than this limit. (<= 0 means ignore this limit)
      ! note: both ``brunt_B`` and ``gradL_composition_term`` come from ``unsmoothed_brunt_B``
      ! and differ only in optional smoothing.
      ! (see ``num_cells_for_smooth_brunt_B`` and ``num_cells_for_smooth_gradL_composition_term``).

      ! ::

    overshoot_brunt_B_max = 0d0


      ! min_overshoot_q
      ! ~~~~~~~~~~~~~~~

      ! Overshooting is only allowed at locations with mass ``m >= min_overshoot_q * mstar``.
      ! E.g., if ``min_overshoot_q = 0.1``, then only the outer 90% by mass can have overshooting.
      ! This provides a simple way of suppressing bogus center overshooting in which a small
      ! convective region at the core can produce excessively large overshooting because of
      ! a large pressure scale height at the center.

      ! ::

    min_overshoot_q = 0d0

      ! NOTE: In addition to giving these 'f' parameters non-zero values, you should also
      ! check the settings for ``mass_for_overshoot_full_on`` and ``mass_for_overshoot_full_off``.


      ! overshoot_alpha
      ! ~~~~~~~~~~~~~~~

      ! The value of Hp for overshooting is limited to the radial thickness
      ! of the convection zone divided by ``overshoot_alpha``.
      ! only used when > 0. If <= 0, then use ``mixing_length_alpha`` instead.

      ! ::

    overshoot_alpha = -1


      ! limit_overshoot_Hp_using_size_of_convection_zone
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if false, allow large distance of overshoot for small convective zones.

      ! ::

    limit_overshoot_Hp_using_size_of_convection_zone = .true.


      ! burn_z_mix_region_logT
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! burn_he_mix_region_logT
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! burn_h_mix_region_logT
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! max logT in convective region determines burn type for overshooting

      ! ::

    burn_z_mix_region_logT = 8.7d0
    burn_he_mix_region_logT = 7.7d0
    burn_h_mix_region_logT = 6.7d0


      ! max_Y_for_burn_z_mix_region
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_X_for_burn_he_mix_region
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Even if a region reaches the above temperature to be considered as
      ! a z_burn region, only set it as such if the helium mass fraction
      ! in all points of the region is below max_Y_for_burn_z_mix_region.
      ! Similarly, max_X_for_burn_he_mix_region controls if a region is
      ! considered as a he_burn region in terms of the hydrogen mass fraction.

      ! ::

    max_Y_for_burn_z_mix_region = 1d-4
    max_X_for_burn_he_mix_region = 1d-4


   ! Predictive mixing
   ! _________________

      ! Predictive mixing is an approach for expanding convective boundaries until
      ! gradr = grada on the convective side of the boundary (as required by the criterion
      ! that the convective velocity and luminosity vanish at the boundary). It is discussed
      ! in detail in Paxton et al. 2018, ApJ, in press: "Modules for Experiments in Stellar
      ! Astrophysics (MESA): Convective boundaries, element diffusion, and massive star explosions"

      ! Predictive mixing is controlled by specifying a set of parameters, which combines matching
      ! criteria (determining which boundaries to apply the predictive mixing to) together with
      ! values (determining how the predictive mixing should operate at those boundaries). Up to
      ! ``NUM_PREDICTIVE_PARAM_SETS`` of these parameter sets can be defined (see ``star_def.inc`` for value).


      ! predictive_mix
      ! ~~~~~~~~~~~~~~

      ! Set to .true. to enable this set of parameters

      ! ::

    predictive_mix(1) = .false.


      ! predictive_zone_type
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Matching criterion for the type of the convection zone. Possible values are ``burn_H``
      ! (hydrogen burning), ``burn_He`` (helium burning), ``burn_Z`` (metal burning), ``nonburn``
      ! (no burning) or ``any`` (which matches any type of zone).

      ! ::

    predictive_zone_type(1) = ''


      ! predictive_zone_loc
      ! ~~~~~~~~~~~~~~~~~~~

      ! Matching criterion for the location of the convection zone. Possible values are ``core``
      ! (the core convection zone), ``shell`` (a convective shell), ``surf`` (the surface convection
      ! zone) or ``any`` (which matches any location).

      ! ::

    predictive_zone_loc(1) = ''


      ! predictive_bdy_loc
      ! ~~~~~~~~~~~~~~~~~~

      ! Matching criterion for the location of the convective boundary. Possible values are
      ! ``top`` (the top of the convection zone), ``bottom`` (the bottom of the convection zone)
      ! or ``any`` (which matches any location).

      ! ::

    predictive_bdy_loc(1) = ''


      ! predictive_bdy_q_min
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Matching criterion for the minimum fractional mass coordinate of the convective
      ! boundary

      ! ::

    predictive_bdy_q_min(1) = 0d0


      ! predictive_bdy_q_max
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Matching criterion for the maximum fractional mass coordinate of the convective
      ! boundary

      ! ::

    predictive_bdy_q_max(1) = 1d0


      ! predictive_superad_thresh
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Threshold for minimum superadiabaticity in the predictive mixing scheme; boundary
      ! expansion stops when gradr/grada-1 drops below this threshold. Default value is usually
      ! good for main-sequence evolution; for core He-burning, set to 0.005, 0.01 or larger
      ! to prevent splitting of the core convection zone and/or core breathing pulses.

      ! ::

    predictive_superad_thresh(1) = 0d0


      ! predictive_avoid_reversal
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Species to monitor for reversals in abundance evolution. If this is set to the name
      ! of a species, then the predictive mixing scheme will try to avoid causing reversals
      ! in the abundance of that species (e.g., changing the abundance evolution from decreasing
      ! to increasing). Set to 'he4' during core He-burning to prevent splitting of the core
      ! convection zone and/or core breathing pulses.

      ! ::

    predictive_avoid_reversal(1) = ''


      ! predictive_limit_ingestion
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! predictive_ingestion_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Limit the rate of ingestion of a species, following the prescription given in
      ! equation (2) of Constantino, Campbell & Lattanzio (2017, MNRAS, 472, 4900). The control
      ! ``predictive_limit_ingestion`` specifies which species to limit, and the control
      ! ``predictive_ingestion_factor`` gives the multiplying factor. Setting this factor to 5/12
      ! is the same as choosing alpha_i = 1 in their equation (2).

      ! ::

    predictive_limit_ingestion(1) = ''
    predictive_ingestion_factor(1) = 0d0


   ! Convective premixing
   ! ____________________

      ! Convective premixing is a approach to handling mixing in convection zones that improves
      ! upon the predictive mixing scheme described above. Like predictive mixing, it expands
      ! convective boundaries until gradr = grada on the convective side of the boundary. Unlike
      ! predictive mixing, it directly modifies abundances in the stellar model, via a iterative
      ! series of mixings-to-homogeneity over a shifting window of cells. This iterative approach
      ! allows convective premixing to build 'classical' semiconvection regions, where the abundance
      ! gradient is tuned to yield convective neutrality.

      ! NOTE: the history columns that give info on the convective and semi convective boundaries
      ! (i.e., ``mass_conv_core`` and ``mass_semiconv_core``) do not work with CPM.
      ! Instead, one should look at the profiles to see where the boundaries are.


      ! do_conv_premix
      ! ~~~~~~~~~~~~~~

      ! Set to .true. to perform convective premixing. Note that this cannot be enabled at the
      ! same time as the ``predictive_mix`` control

      ! ::

    do_conv_premix = .false.


      ! do_premix_heating
      ! ~~~~~~~~~~~~~~~~~

      ! if true, calculate heating term associated with changes in
      ! internal energy due to any abundance changes from convective
      ! premixing, and include this term in the energy equation.

      ! ::

    do_premix_heating = .true.


      ! conv_premix_avoid_increase
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Attempt to avoid increases in the abundance of species being burned. Sometimes, the
      ! convective premixing scheme can cause the abundance of a species being burned (e.g.,
      ! helium during core helium burning) to increase across a timestep. This typically arises
      ! when the scheme mixes a fresh supply of the species into the convection zone where the
      ! burning is occurring. Setting the ``conv_premix_avoid_increase`` control to .true. will
      ! tell the scheme to avoid such outcomes, if possible. In the case of core helium burning,
      ! this helps to reduces the incidences of core breathing pulses (although in some situations
      ! it doesn't completely eliminate them).

      ! ::

    conv_premix_avoid_increase = .false.


      ! conv_premix_time_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Scaling factor for deciding whether a convective boundary has enough time to advance during
      ! a timestep. Simple physical arguments suggest that a convective boundary requires a time
      ! delta_t ~ delta_r/v_conv to advance a distance delta_r. The convective premixing algorithm
      ! keeps a tally of how much time a boundary has spent advancing, and it prevents further advancing
      ! if this time would exceed conv_premix_time_factor*dt, where dt is the current timestep. Setting
      ! conv_premix_time_factor to a value <= 0 disables this check. STILL UNDER DEVELOPMENT, AND DISABLED
      ! BY DEFAULT

      ! ::

    conv_premix_time_factor = 0.0

      ! conv_premix_fix_pgas
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Flag to decide whether gas pressure is kept constant during premixing (.true.), or instead
      ! density is kept constant (.false.). In both cases, temperature is kept constant.

      ! ::

    conv_premix_fix_pgas = .true.

      ! conv_premix_dump_snapshots
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Flag to write out snapshots of the intermediate stages during the convective premixing iterations.
      ! Refer to the ``dump_snapshot_`` routine in star/private/conv_premix.f90 to see what's written out. Note
      ! that this can quickly fill up your disk!

      ! ::

    conv_premix_dump_snapshots = .false.


   ! Rayleigh-Taylor Instability
   ! ____________________________

      ! derived from Paul Duffell's code RT1D.


      ! RTI_smooth_mass
      ! ~~~~~~~~~~~~~~~
      ! RTI_smooth_iterations
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! RTI_smooth_fraction
      ! ~~~~~~~~~~~~~~~~~~~

      ! smoothing for ``dPdr_dRhodr_info``
      ! done at start of step

      ! ::

    RTI_smooth_mass = 0d0
    RTI_smooth_iterations = 0
    RTI_smooth_fraction = 1d0


      ! alpha_RTI_diffusion_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! dudt_RTI_diffusion_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! dedt_RTI_diffusion_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! dlnddt_RTI_diffusion_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! composition_RTI_diffusion_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_M_RTI_factors_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_M_RTI_factors_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    alpha_RTI_diffusion_factor = 1d0
    dudt_RTI_diffusion_factor = 1d0
    dedt_RTI_diffusion_factor = 1d0
    dlnddt_RTI_diffusion_factor = 1d0
    composition_RTI_diffusion_factor = 1d0
    max_M_RTI_factors_full_on = 1d99
    min_M_RTI_factors_full_off = 1d99


      ! alpha_RTI_src_max_q
      ! ~~~~~~~~~~~~~~~~~~~
      ! alpha_RTI_src_min_q
      ! ~~~~~~~~~~~~~~~~~~~

      ! option to set ``alpha_RTI`` source term to zero when cell q out of bounds.
      ! to turn off RTI near surface or center

      ! ::

    alpha_RTI_src_max_q = 1d0
    alpha_RTI_src_min_q = 0d0


      ! alpha_RTI_src_min_v_div_cs
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! option to set alpha_RTI source term to zero when v/cs < this min.
      ! e.g. to filter out false sources ahead of shock

      ! ::

    alpha_RTI_src_min_v_div_cs = 1d0


      ! Radial Stellar Pulsations (RSP)
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! inspired by Radec Smolec's Program

      ! must set mass, Teff, L, X, and Z.

      ! ::

    RSP_mass = -1
    RSP_Teff = -1
    RSP_L = -1
    RSP_X = -1
    RSP_Z = -1

      ! Parameters of the convection model.
      ! Note that ``RSP_alfap``, ``RSP_alfas``, ``RSP_alfac``, ``RSP_alfad`` and ``RSP_gammar``
      ! are expressed in the units of standard values.
      ! Standard values are the ones for which static version of the Kuhfuss
      ! model reduces to standard MLT. See Table 1 in `Smolec & Moskalik (2008)`_
      ! for standard values and the description of the parameters.

      ! .. _Smolec & Moskalik (2008): https://ui.adsabs.harvard.edu/abs/2008AcA....58..193S

      ! ::

    RSP_alfa = 1.5d0            ! mixing length; alfa = 0 gives a purely radiative model.
    RSP_alfac = 1.0d0           ! convective flux; Lc ~ RSP_alfac
    RSP_alfas = 1.0d0           ! turbulent source; Lc ~ 1/ALFAS; PII ~ RSP_alfas
    RSP_alfad = 1.0d0           ! turbulent dissipation; damp ~ RSP_alfad
    RSP_alfap = 0.0d0           ! turbulent pressure; Pt ~ alfap
    RSP_alfat = 0.0d0           ! turbulent flux; Lt ~ RSP_alfat; overshooting.
    RSP_alfam = 0.25d0          ! eddy viscosity; Chi & Eq ~ RSP_alfam
    RSP_gammar = 0.0d0          ! radiative losses; dampR ~ RSP_gammar

      ! time weighting for end-of-step vs start-of-step values in equations.
      ! 1 corresponds to fully implicit scheme - stable, but can have large numerical damping.
      ! 0.5 corresponds to trapezoidal rule integration - gives least numerical damping.
      ! do not use values less than 0.5.  Strongly recommend 0.5 for theta and thetat.
      ! don't mess with any of these unless you know what you are doing or like to watch the code crash.

      ! ::

    RSP_theta = 0.5d0           ! Pgas and Prad
    RSP_thetat = 0.5d0          ! Pturb
    RSP_thetae = 0.5d0          ! erad in terms using f_Edd
    RSP_thetaq = 1.0d0          ! Pvsc
    RSP_thetau = 1.0d0          ! Eq and Uq
    RSP_wtr = 0.6667d0          ! Lr
    RSP_wtc = 0.6667d0          ! Lc
    RSP_wtt = 0.6667d0          ! Lt
    RSP_gam = 1.0d0             ! Et src_snk

      ! controls for building the initial model

      ! ::

    RSP_nz = 150
    RSP_nz_outer = 40
    RSP_T_anchor = 11d3
    RSP_T_inner = 2d6
    RSP_testing = .false.

      ! ::

    RSP_dq_1_factor = 2d0
    RSP_max_outer_dm_tries = 100
    RSP_max_inner_scale_tries = 100
    RSP_T_anchor_tolerance = 1d-8

      ! allowed relative difference between T at base of outer region and T_anchor
      ! if fail trying to create initial model, try increasing this to 1d-6 or more

      ! ::

    RSP_T_inner_tolerance = 1d-8

      ! allowed relative difference between T at inner boundary and T_inner
      ! if fail trying to create initial model, try increasing this to 1d-6 or more

      ! ::

    RSP_relax_initial_model = .true.
    RSP_relax_alfap_before_alfat = .true.
    RSP_relax_max_tries = 1000
    RSP_relax_dm_tolerance = 1d-6

      ! Initial kick makes use of the scaled linear velocity eigenvector
      ! of a given mode or of the linear combination of the eigenvectors
      ! for the fundamental mode and first two radial overtones.
      ! The surface velocity is set to RSP_kick_vsurf_km_per_sec and
      ! the mode content is set by RSP_fraction_1st_overtone and RSP_fraction_2nd_overtone

      ! ::

    RSP_kick_vsurf_km_per_sec = 0.1d0
    RSP_fraction_1st_overtone = 0d0
    RSP_fraction_2nd_overtone = 0d0

      ! fraction from fundamental = 1d0 - (1st + 2nd)
      ! Note: This is important for models in which two or more modes are linearly unstable.
      ! Appropriate setting may help to arrive at the desired mode, since the final pulsation
      ! state may depend on initial conditions set by the three parameters above.
      ! Integration of the same model with different initial kicks is a way to study
      ! the nonlinear mode selection - for an example see Fig. 1 in `Smolec & Moskalik (2010)`_.

      ! .. _Smolec & Moskalik (2010): https://ui.adsabs.harvard.edu/abs/2010A%26A...524A..40S

      ! random initial velocity profile.  Added to any kick from eigenvector.

      ! ::

    RSP_Avel = 0d0
    RSP_Arnd = 0d0

      ! period controls

      ! ::

    RSP_target_steps_per_cycle = 600
    RSP_min_max_R_for_periods = -1
    RSP_min_deltaR_for_periods = -1
    RSP_min_PERIOD_div_PERIODLIN = 0.5d0
    RSP_mode_for_setting_PERIODLIN = 1
    RSP_default_PERIODLIN = 34560

      ! when to stop

      ! ::

    RSP_max_num_periods = -1
    RSP_GREKM_avg_abs_frac_new = 0.1d0
    RSP_GREKM_avg_abs_limit = -1

      ! timestep limiting

      ! ::

    RSP_initial_dt_factor = 1d-2

      ! start with smaller timestep to give time for initial model to adjust

      ! ::

    RSP_v_div_cs_threshold_for_dt_limit = 0.8d0
    RSP_max_dt_times_min_dr_div_cs = 2d0

      ! i.e., make dt <= this times min sound crossing time dr/cs
      ! only considering cells with abs(v)/cs > threshold

      ! ::

    RSP_max_dt_times_min_rad_diff_time = -1d0

      ! make dt <= min time for radiative diffusion for RHD

      ! ::

    RSP_max_dt = -1
    RSP_report_limit_dt = .false.

      ! artificial viscosity controls
      ! for the equations see: Appendix C in `Stellingwerf (1975)`_.
      ! In principle, for not too-non-adiabatic convective models artificial viscosity is not
      ! needed or should be very small. Hence a large cut-off parameter below (in purely
      ! radiative models the default value for cut-off was 0.01)

      ! .. _Stellingwerf (1975): https://ui.adsabs.harvard.edu/abs/1975ApJ...195..441S

      ! ::

    RSP_cq = 4.0d0
    RSP_zsh = 0.1d0

      ! zsh > 0 delays onset of artificial viscosity
      ! can eliminate most/all interior dissipation while still providing for extreme cases.
      ! using this parameter the dependence of limiting amplitude on cq is very weak.
      ! for Tscharnuter & Winkler form of artificial viscosity

      ! ::

    RSP_Qvisc_linear = 0d0
    RSP_Qvisc_quadratic = 0d0

      ! as described in section 4.2 of mesa3, 2015.
      ! RSP_Qvisc_linear is analogous to shock_spread_linear
      ! RSP_Qvisc_quadratic is analogous to shock_spread_quadratic
      ! if switch to this form, set RSP_cq = 0 to shut off the Neumann & Richtmyer form.
      ! note that this form also uses RSP_zsh to delay onset of artificial viscosity

      ! surface pressure.  Provides outer boundary condition for momentum equation.

      ! ::

    RSP_use_Prad_for_Psurf = .false.
    RSP_use_atm_grey_with_kap_for_Psurf = .false.
    RSP_tau_surf_for_atm_grey_with_kap = 3d-3
    RSP_fixed_Psurf = .true.
    RSP_Psurf = 0d0
    set_RSP_Psurf_to_multiple_of_initial_P1 = -1

      ! set RSP_Psurf to this times initial surface cell pressure

      ! ::

    RSP_surface_tau = 0.001d0

      ! solver controls

      ! ::

    RSP_tol_max_corr = 1d-8
    RSP_tol_max_resid = 1d-6
    RSP_max_iters_per_try = 100
    RSP_max_retries_per_step = 50
    RSP_report_undercorrections = .false.
    RSP_nz_div_IBOTOM = 30d0
    RSP_min_tau_for_turbulent_flux = 2d2

      ! output data for work integrals during a particular period

      ! ::

    RSP_work_period = -1
    RSP_work_filename = 'work.data'

      ! output data for 3d map.  Format same as for gnuplot pm3d

      ! ::

    RSP_write_map = .false.
    RSP_map_columns_filename = 'map_columns.list'

      ! items listed in your map columns must also appear in your profile columns

      ! ::

    RSP_map_filename = 'map.data'
    RSP_map_first_period = -1
    RSP_map_last_period = -1
    RSP_map_zone_interval = 2
    RSP_map_history_filename = 'map_history.data'

      ! rsp hooks

      ! ::

    use_other_RSP_linear_analysis = .false.
    use_other_RSP_build_model = .false.

      ! for special tests
      ! can set ALFA = 0 for pure radiative with no turbulence or convection.
      ! can set zero_gravity = .true.
      ! can set opacity to be constant times density.

      ! ::

    RSP_kap_density_factor = -1

      ! else set opacity to this times density

      ! rsp misc

      ! ::

    RSP_efl0 = 1.0d2
    RSP_nmodes = 3
    RSP_trace_RSP_build_model = .false.

      ! ::

    use_RSP_new_start_scheme = .false.

      ! ::

    RSP_Qvisc_linear_static = 0d0

      ! ::

    RSP_relax_adjust_inner_mass_distribution = .true.

      ! ::

    RSP_do_check_omega = .true.

      ! ::

    RSP_report_check_omega_changes = .false.

      ! ::

    RSP_hydro_only = .false.

      ! this does not work with the standard build model, so requires use_other_RSP_build_model


   ! mixing misc
   ! ___________

      ! such as smoothing and editing of diffusion coefficients


      ! mix_factor
      ! ~~~~~~~~~~

      ! Mixing coefficients are multiplied by this factor.
      ! The ``mix_factor`` is applied in subroutine ``get_convection_sigmas`` in ``star/private/mix_info.f90`` --
      ! the lagrangian diffusion coefficient sigma(k) at cell boundary k is set to
      ! ``mix_factor*D*(4*pi*r(k)^2*rho_face(k))^2``.
      ! Note that the value of D is not changed -- it is just used as a term in calculating sigma.

      ! ::

    mix_factor = 1


      ! max_conv_vel_div_csound
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! convective velocities are limited to local sound speed times this factor.

      ! ::

    max_conv_vel_div_csound = 1d99


      ! max_conv_vel_div_csound_maxq
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! only consider ``max_conv_vel_div_csound`` from center out to this location

      ! ::

    max_conv_vel_div_csound_maxq = -1

      ! max_v_for_convection
      ! ~~~~~~~~~~~~~~~~~~~~

      ! disable convection for locations with v > than this limit. In km/s.

      ! ::

    max_v_for_convection = 1d99


      ! max_q_for_convection_with_hydro_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! disable convection for locations with q > than this limit when
      ! either v_flag or u_flag are true.

      ! ::

    max_q_for_convection_with_hydro_on = 1d99


      ! max_v_div_cs_for_convection
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! disable convection for locations with abs(v)/cs > this limit

      ! ::

    max_v_div_cs_for_convection = 1d99


      ! max_abs_du_div_cs_for_convection
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! main purpose is to force radiative in shock face

      ! ::

    max_abs_du_div_cs_for_convection = 0.03d0


      ! prune_bad_cz_min_Hp_height
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Lower limit on radial extent of cz (<= 0 to disable).
      ! In units of average pressure scale height at top and bottom of region.
      ! Remove tiny convection zones unless have strong nuclear burning
      ! This allows emergence of very small cz at site of he core flash, for example.
      ! i.e., remove if ``size < prune_bad_cz_min_Hp_height`` .and.
      ! ``max_log_eps < prune_bad_cz_min_log_eps_nuc``.

      ! ::

    prune_bad_cz_min_Hp_height = 0


      ! prune_bad_cz_min_log_eps_nuc
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Lower limit on max log eps nuc in cz.
      ! remove if ``size < prune_bad_cz_min_Hp_height`` .and.
      ! ``max_log_eps < prune_bad_cz_min_log_eps_nuc``.

      ! ::

    prune_bad_cz_min_log_eps_nuc = -99


      ! redo_conv_for_dr_lt_mixing_length
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Check for small convection zones with total height less than mixing length
      ! and redo with reduced ``mixing_length_alpha`` to make ``mixing_length <= dr``.

      ! ::

    redo_conv_for_dr_lt_mixing_length = .false.


      ! smooth_convective_bdy
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! ``smooth_convective_bdy`` has been removed.

      ! remove_mixing_glitches
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! If true, then okay to remove gaps and singletons.

      ! ::

    remove_mixing_glitches = .true.


   ! glitches
   ! ________

      ! The following controls are for different kinds of "glitches" that can be removed.


      ! okay_to_remove_mixing_singleton
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, remove singletons.

      ! ::

    okay_to_remove_mixing_singleton = .true.


      ! clip_D_limit
      ! ~~~~~~~~~~~~

      ! Zero mixing diffusion coeffs that are smaller than this.

      ! ::

    clip_D_limit = 0


      ! min_convective_gap
      ! ~~~~~~~~~~~~~~~~~~

      ! Close gap between convective regions if smaller than this (< 0 means skip this).
      ! Gap measured radially in units of pressure scale height.

      ! ::

    min_convective_gap = -1


      ! min_thermohaline_gap
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Close gap between thermohaline mixing regions if smaller than this (< 0 means skip this).
      ! Gap measured radially in units of pressure scale height.

      ! ::

    min_thermohaline_gap = -1


      ! min_thermohaline_dropout
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_dropout_gradL_sub_grada
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If find radiative region embedded in thermohaline,
      ! and ``max(gradL - grada)`` in region is everywhere ``< max_dropout_gradL_sub_grada``
      ! and region height is ``< min_thermohaline_dropout``
      ! then convert the region to thermohaline.
      ! ``min_thermohaline_dropout <= 0`` disables.

      ! ::

    min_thermohaline_dropout = -1
    max_dropout_gradL_sub_grada = 1d-3


      ! min_semiconvection_gap
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Close gap between semiconvective mixing regions if smaller than this (< 0 means skip this).
      ! Gap measured radially in units of pressure scale height.

      ! ::

    min_semiconvection_gap = -1


      ! remove_embedded_semiconvection
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If have a semiconvection region bounded on each side by convection,
      ! convert it to be convective too.

      ! ::

    remove_embedded_semiconvection = .false.


      ! recalc_mix_info_after_evolve
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Re-evaluate mixing info after each evolve step. This is helpful if you want the profiles to
      ! reflect the mixing params after the step; otherwise, they give the mixing info from the start
      ! of the step (i.e., one step out-of-date)

      ! ::

    recalc_mix_info_after_evolve = .false.


      ! set_min_D_mix
      ! ~~~~~~~~~~~~~
      ! mass_lower_limit_for_min_D_mix
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! mass_upper_limit_for_min_D_mix
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_D_mix
      ! ~~~~~~~~~

      ! ``D_mix`` will be at least this large if ``set_min_D_mix`` is true.
      ! doesn't apply for mass < lower limit or mass > upper limit.

      ! ::

    set_min_D_mix = .false.
    mass_lower_limit_for_min_D_mix = 0d0
    mass_upper_limit_for_min_D_mix = 1d99
    min_D_mix = 1d3


      ! set_min_D_mix_in_H_He
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! min_D_mix_in_H_He
      ! ~~~~~~~~~~~~~~~~~

      ! ``D_mix`` will be at least this large in regions
      ! where max mass fractions of H and He add to more that 0.5
      ! if ``set_min_D_mix_in_H_He`` is true.

      ! ::

    set_min_D_mix_in_H_He = .false.
    min_D_mix_in_H_He = 1d3


      ! set_min_D_mix_below_Tmax
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_D_mix_below_Tmax
      ! ~~~~~~~~~~~~~~~~~~~~

      ! ``D_mix`` will be at least this large for cells below location of max temperature
      ! if ``set_min_D_mix_below_Tmax`` is true.

      ! ::

    set_min_D_mix_below_Tmax = .false.
    min_D_mix_below_Tmax = 1d3


      ! min_center_Ye_for_min_D_mix
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ``min_D_mix`` is only used when ``center_ye >= this``
      ! i.e., when ``center_ye`` drops below this, ``min_D_mix = 0``.

      ! ::

    min_center_Ye_for_min_D_mix = 0.47d0


      ! smooth_outer_xa_big
      ! ~~~~~~~~~~~~~~~~~~~
      ! smooth_outer_xa_small
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Soften composition jumps in outer layers.
      ! If ``smooth_outer_xa_big`` and ``smooth_outer_xa_small`` are bigger than 0, then
      ! starting from the outermost grid point, homogeneously mix a region of size
      ! ``smooth_outer_xa_small`` (in solar masses), and proceed inwards, linearly reducing
      ! the size of the homogeneously mixed region in such a way that it becomes zero.
      ! After going ``smooth_outer_xa_big`` solar masses in. In this way, the outer ``smooth_outer_xa_big``
      ! solar masses are "cleaned" of composition jumps.

      ! ::

    smooth_outer_xa_big = -1d0
    smooth_outer_xa_small = -1d0


! rotation controls
! =================

      ! In the following "am" stands for "angular momentum".

      ! the mesa implementation of rotation closely follows these papers:

      ! + Heger, Langer, & Woosley, ApJ, 528, 368.  2000
      ! + Heger, Woosley, & Spruit, ApJ, 626, 350.  2005

      ! + ``D_DSI`` = dynamical shear instability
      ! + ``D_SH`` = Solberg-Hoiland
      ! + ``D_SSI`` = secular shear instability
      ! + ``D_ES`` = Eddington-Sweet circulation
      ! + ``D_GSF`` = Goldreich-Schubert-Fricke
      ! + ``D_ST`` = Spruit-Tayler dynamo


      ! skip_rotation_in_convection_zones
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if true, then set rotational diffusion coefficients to 0 in convective regions.
      ! This applies both for material mixing and diffusion of angular momentum.

      ! ::

    skip_rotation_in_convection_zones = .false.


      ! am_D_mix_factor
      ! ~~~~~~~~~~~~~~~

      ! Rotation and mixing of material.
      ! ``D_mix`` = diffusion coefficient for mixing of material.
      ! It is sum of non-rotational and rotational components.
      ! The rotational part is multiplied by this factor.

      ! ::

      !     D_mix = D_mix_non_rotation + f*am_D_mix_factor*(
      !         D_DSI_factor * D_DSI +
      !         D_SH_factor  * D_SH +
      !         D_SSI_factor * D_SSI +
      !         D_ES_factor  * D_ES +
      !         D_GSF_factor * D_GSF +
      !         D_ST_factor  * D_ST)

      ! ::

      !     f = 1  when logT <= D_mix_rotation_max_logT_full_on = full_on
      !       = 0  when logT >= D_mix_rotation_min_logT_full_off = full_off
      !       = (log(T)-full_on)/(full_off-full_on) else

      ! note that for regions with brunt N^2 < 0, we set Richardson number to 1
      ! which is > Ri_critical and therefore turns off DSI and SSI

      ! according to Heger et al 2000 : 1/30d0
      ! by default : 0

      ! ::

    am_D_mix_factor = 0


      ! am_nu_factor
      ! ~~~~~~~~~~~~
      ! am_nu_non_rotation_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! diffusion of angular momentum

      ! ``am_nu`` = diffusion coefficient for angular momentum

      ! ::

      !     am_nu_non_rot = am_nu_factor*am_nu_non_rotation_factor*D_mix_non_rotation
      !     am_nu_rot = am_nu_factor*(
      !         am_nu_visc_factor* D_visc +
      !         am_nu_DSI_factor * D_DSI +
      !         am_nu_SH_factor  * D_SH +
      !         am_nu_SSI_factor * D_SSI +
      !         am_nu_ES_factor  * D_ES +
      !         am_nu_GSF_factor * D_GSF +
      !         am_nu_ST_factor  * nu_ST)
      !     am_nu = am_nu_non_rot + am_nu_rot

      ! Note that for regions with brunt N^2 < 0, we set Richardson number to 1
      ! which is > Ri_critical and therefore turns off DSI and SSI.

      ! see also ``star_job`` controls for ``am_nu_rot_flag``

      ! ::

    am_nu_factor = 1
    am_nu_non_rotation_factor = 1


      ! am_nu_DSI_factor
      ! ~~~~~~~~~~~~~~~~

      ! < 0 means use ``D_DSI_factor``

      ! ::

    am_nu_DSI_factor = -1


      ! am_nu_SSI_factor
      ! ~~~~~~~~~~~~~~~~

      ! < 0 means use ``D_SSI_factor``

      ! ::

    am_nu_SSI_factor = -1


      ! am_nu_SH_factor
      ! ~~~~~~~~~~~~~~~

      ! < 0 means use ``D_SH_factor``

      ! ::

    am_nu_SH_factor = -1


      ! am_nu_ES_factor
      ! ~~~~~~~~~~~~~~~

      ! < 0 means use ``D_ES_factor``

      ! ::

    am_nu_ES_factor = -1


      ! am_nu_GSF_factor
      ! ~~~~~~~~~~~~~~~~

      ! < 0 means use ``D_GSF_factor``

      ! ::

    am_nu_GSF_factor = -1


      ! am_nu_ST_factor
      ! ~~~~~~~~~~~~~~~

      ! < 0 means use ``D_ST_factor``

      ! ::

    am_nu_ST_factor = -1


      ! am_nu_visc_factor
      ! ~~~~~~~~~~~~~~~~~

      ! < 0 means use ``D_visc_factor``.
      ! By default = 1 to mix angular momentum.

      ! ::

    am_nu_visc_factor = 1


      ! am_nu_omega_rot_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! am_nu_omega_non_rot_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      !     dj/dt = d/dm((4 pi r^2 rho)^2*(am_nu_omega*i_rot*domega/dm + am_nu_j*dj/dm))
      !     am_nu_omega = am_nu_omega_non_rot_factor*am_nu_non_rot + am_nu_omega_rot_factor*am_nu_rot

      ! ::

    am_nu_omega_rot_factor = 1
    am_nu_omega_non_rot_factor = 1


      ! am_nu_j_rot_factor
      ! ~~~~~~~~~~~~~~~~~~
      ! am_nu_j_non_rot_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~

      !     dj/dt = d/dm((4 pi r^2 rho)^2*(am_nu_omega*i_rot*domega/dm + am_nu_j*dj/dm))
      !     am_nu_j = am_nu_j_non_rot_factor*am_nu_non_rot + am_nu_j_rot_factor*am_nu_rot

      ! ::

    am_nu_j_rot_factor = 0
    am_nu_j_non_rot_factor = 0


      ! set_uniform_am_nu_non_rot
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! uniform_am_nu_non_rot
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! You can specify a uniform value for ``am_nu_non_rot`` by setting this flag true.
      ! A large uniform ``am_nu`` will produce a uniform omega.

      ! ::

    set_uniform_am_nu_non_rot = .false.
    uniform_am_nu_non_rot = 1d20


      ! set_min_am_nu_non_rot
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! min_am_nu_non_rot
      ! ~~~~~~~~~~~~~~~~~

      ! You can also specify a minimum ``am_nu_non_rot``.
      ! ``am_nu`` will be at least this large.

      ! ::

    set_min_am_nu_non_rot = .false.
    min_am_nu_non_rot = 1d8


      ! min_center_Ye_for_min_am_nu_non_rot
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ``min_am_nu_non_rot`` is only used when center Ye >= this.

      ! ::

    min_center_Ye_for_min_am_nu_non_rot = 0.47d0

      ! Each rotationally induced diffusion coefficient has a factor that lets you control it.
      ! Value of 1 gives normal strength; value of 0 turns it off.

      ! Note that for regions with brunt N^2 < 0, we set Richardson number to 1,
      ! which is > Ri_critical and therefore turns off DSI and SSI.

      ! ::

    D_DSI_factor = 0
    D_SH_factor = 0
    D_SSI_factor = 0
    D_ES_factor = 0
    D_GSF_factor = 0
    D_ST_factor = 0


      ! D_visc_factor
      ! ~~~~~~~~~~~~~

      ! Kinematic shear viscosity.
      ! Should be = 0 because viscosity doesn't mix chemical elements.

      ! ::

    D_visc_factor = 0


      ! am_gradmu_factor
      ! ~~~~~~~~~~~~~~~~

      ! Sensitivity to composition gradients.
      ! In calculation of rotational induced mixing, ``grad_mu`` is multiplied by ``am_gradmu_factor``.
      ! Value from from Heger et al 2000.

      ! ::

    am_gradmu_factor = 0.05d0

      ! Spatial smoothing is used in calculations of diffusion coefficients.
      ! These control the smoothing window widths (number of cells on each side).

      ! ::

    smooth_D_DSI = 0
    smooth_D_SH = 0
    smooth_D_SSI = 0
    smooth_D_ES = 0
    smooth_D_GSF = 0
    smooth_D_ST = 0
    smooth_nu_ST = 0
    smooth_D_omega = 0
    smooth_am_nu_rot = 0


      ! ST_angsmt
      ! ~~~~~~~~~
      ! ST_angsml
      ! ~~~~~~~~~

      ! Temporal smoothing of ST coefficients.
      ! See rotation_mix_info.f90 for details

      ! ::

    ST_angsmt = 0.2d0
    ST_angsml = 1d-3


      ! simple_i_rot_flag
      ! ~~~~~~~~~~~~~~~~~

      ! If true, ``i_rot = (2/3)*r^2``.
      ! If false, use slightly more complex expression
      ! that takes into account finite shell thickness.
      ! In practice, there doesn't seem to be a significant difference.

      ! ::

    simple_i_rot_flag = .false.


      ! do_adjust_J_lost
      ! ~~~~~~~~~~~~~~~~
      ! adjust_J_fraction
      ! ~~~~~~~~~~~~~~~~~
      ! min_q_for_adjust_J_lost
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! min_J_div_delta_J
      ! ~~~~~~~~~~~~~~~~~

      ! adjust angular momentum
      ! With do_adjust_J_lost = .false., the angular momentum removed via winds
      ! from the star corresponds to that contained in the removed layers.
      ! However, since j_rot can increase steeply in the very outer layers,
      ! very small steps are required to obtain a convergent solution. To avoid
      ! this, the do_adjust_J_lost option adjusts the angular momentum content
      ! of layers below those removed, such that

      ! ::

      !     actual_J_lost = &
      !        adjust_J_fraction*mass_lost*s% j_rot_surf + &
      !        (1d0 - adjust_J_fraction)*s% angular_momentum_removed

      ! where s% angular_momentum_removed is the angular momentum contained
      ! in the removed layers of the star in that step. Note that
      ! s% angular_momentum_removed is set to actual_J_lost after this.

      ! The region from which angular momentum is removed is chosen such that
      ! at its bottom q<min_q_for_adjust_J_lost, it contains at least
      ! min_J_div_delta_J times the angular momentum that needs to be accounted
      ! for. Angular momentum in these regions is adjusted in such a way that
      ! no artificial shear is produced at the inner boundary.

      ! This can also be used to model mass loss mechanisms that remove more
      ! angular momentum than mass_lost*s% j_rot_surf, for instance magnetic
      ! braking or wind mass loss. In that case, you can use the
      ! use_other_j_for_adjust_J_lost option to specify a specific angular momentum
      ! of removed material different from j_rot_surf

      ! In order to prevent the algorithm from digging to deep to adjust J,
      ! there is a timestep limit adjust_J_q_limit

      ! ::

    do_adjust_J_lost = .true.
    adjust_J_fraction = 1d0
    min_q_for_adjust_J_lost = 0.995d0
    min_J_div_delta_J = 3d0


      ! premix_omega
      ! ~~~~~~~~~~~~

      ! if premix_omega is true, then do 1/2 of the transport of angular momentum
      ! before updating the structure and 1/2 after.
      ! otherwise, do all of the transport after updating the structure.
      ! RECOMMENDED to turn it on when modelling an accreting star or when
      ! using do_adjust_J_lost.

      ! ::

    premix_omega = .true.


      ! angular_momentum_error_warn
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! angular_momentum_error_retry
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if the relative change in total angular momentum exceeds these values,
      ! then a warning is given on the terminal output, or the simulation is stopped
      ! altogether. Not applied when using other_torque routines or for binaries.

      ! ::

    angular_momentum_error_warn = 5d-6
    angular_momentum_error_retry = 1d-6


      ! recalc_mixing_info_each_substep
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if ``recalc_mixing_info_each_substep`` is true, then recalculate the omega mixing coefficients after each substep of the solve omega mix process.

      ! ::

    recalc_mixing_info_each_substep = .false.

      ! w_div_wcrit_max
      ! ~~~~~~~~~~~~~~~

      ! Maximum value for ``w_div_w_crit_roche``. When ``w_div_wc_flag`` is false (default),
      ! this is a hard limit. When ``w_div_wc_flag`` is true, this works together with
      ! ``w_div_wcrit_max2`` to provide a smooth transition (see below).

      ! ::

    w_div_wcrit_max = 0.89d0


      ! w_div_wcrit_max2
      ! ~~~~~~~~~~~~~~~~

      ! When w_div_wc_flag is true, rather than a hard limit on w_div_wcrit
      ! we use two limiting values w_div_wcrit_max < w_div_wcrit_max2 to provide a smooth transition.
      ! Nothing is done when w_div_wc < w_div_wcrit_max, if w_div_wcrit_max < w_div_wc < w_div_wcrit_max2,
      ! we apply a sigmoid, and in the limit of j_rot -> infinity, the resulting w_div_wc will match
      ! w_div_wcrit_max2 (being on the top of the sigmoid)

      ! ::

    w_div_wcrit_max2 = 0.90d0


      ! D_mix_rotation_max_logT_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Use rotational components of ``D_mix`` for locations where logT <= this.
      ! For numerical stability, turn off rotational part of ``D_mix`` at very high T.

      ! ::

    D_mix_rotation_max_logT_full_on = 9.4d0


      ! D_mix_rotation_min_logT_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Drop rotational components of ``D_mix`` for locations where logT >= this.
      ! For numerical stability, turn off rotational part of ``D_mix`` at very high T.

      ! ::

    D_mix_rotation_min_logT_full_off = 9.5d0


      ! D_mix_rotation_min_tau_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Drop rotational components of ``D_mix`` for locations where tau <= this.
      ! For numerical stability, turn off rotational part of ``D_mix`` at very low tau.

      ! ::

    D_mix_rotation_min_tau_full_off = 0d0

      ! D_mix_rotation_min_tau_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Use rotational components of ``D_mix`` for locations where tau >= this.
      ! For numerical stability, turn off rotational part of ``D_mix`` at very low tau.

      ! ::

    D_mix_rotation_min_tau_full_on = 0d0


      ! D_omega_mixing_rate
      ! ~~~~~~~~~~~~~~~~~~~
      ! D_omega_mixing_across_convection_boundary
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_q_for_D_omega_zero_in_convection_region
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ``D_omega_mixing_across_convection_boundary`` was previously called ``D_omega_mixing_in_convection_regions``.

      ! ::

    D_omega_mixing_rate = 1d0
    D_omega_mixing_across_convection_boundary = .false.
    max_q_for_D_omega_zero_in_convection_region = 0.8d0


      ! nu_omega_mixing_rate
      ! ~~~~~~~~~~~~~~~~~~~~
      ! nu_omega_mixing_across_convection_boundary
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_q_for_nu_omega_zero_in_convection_region
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    nu_omega_mixing_rate = 1d0
    nu_omega_mixing_across_convection_boundary = .false.
    max_q_for_nu_omega_zero_in_convection_region = 0.8d0


! atmosphere boundary conditions
! ==============================


      ! atm_option
      ! ~~~~~~~~~~

      ! Controls how the surface temperature Tsurf and pressure Psurf are evaluated when
      ! setting up outer boundary conditions. We caution that the use of ``'fixed_'`` atmosphere
      ! options might conflict with MLT_option = ``TDC``.

      ! + ``'T_tau'``:
      !   set Tsurf and Psurf by solving for the atmosphere structure given a T(tau) relation.
      !   The choice of relation is set by the ``atm_T_tau_relation`` control. See also
      !   the ``atm_T_tau_opacity``, ``atm_T_tau_errtol``, ``atm_T_tau_max_iters`` and
      !   ``atm_T_tau_max_steps`` controls.
      !
      ! + ``'table'``:
      !   set Tsurf and Psurf by interpolating in pre-calculated tables based on model
      !   atmospheres. The choice of table is set by the ``atm_table`` control.
      !   Requires tau_factor = 1, as surface of the model must always attach at the base
      !   of the tables, so there is no flexibility to move model surface inward or outward.
      !   Note that tau_base = tau_surf is the location at which the model attaches to the
      !   table BCs, and there is no particular location identified as the photosphere, so
      !   we fall back to the surface values of L, R, and m to calculate quantities such as
      !   Teff and log_g. This is consistent with the assumptions used for table construction:
      !   geometrically thin atmospheres with constant flux.
      !
      ! + ``'irradiated_grey'``:
      !   set Tsurf by solving for the atmosphere structure given the irradiated-grey
      !   T(tau) relation of Guillot, T, and Havel, M., A&A 527, A20 (2011).
      !   See also the ``atm_irradiated_opacity``, ``atm_irradiated_errtol``, ``atm_irradiated_T_eq``,
      !   ``atm_irradiated_kap_v``, ``atm_irradiated_kap_v_div_kap_th``,
      !   ``atm_irradiated_P_surf`` and ``atm_irradiated_max_iters`` controls.
      !
      ! + ``'fixed_Teff'`` :
      !    set Tsurf from Eddington T(tau) relation
      !    for current surface tau and Teff = ``atm_fixed_Teff``.
      !    set Psurf = Radiation_Pressure(Tsurf)
      !
      ! + ``'fixed_Tsurf'`` :
      !    get value of Tsurf from control parameter ``atm_fixed_Tsurf``.
      !    set Teff from Eddington T(tau) relation for given Tsurf and tau=2/3
      !    set Psurf = Radiation_Pressure(Tsurf)
      !
      ! + ``'fixed_Psurf'`` :
      !    get value of Psurf from control parameter ``atm_fixed_Psurf``.
      !    set Tsurf from L and R using ``L = 4*pi*R^2*boltz_sigma*T^4``.
      !    set Teff using Eddington T(tau) relation for tau=2/3 and T=Tsurf.
      !
      ! + ``'fixed_Psurf_and_Tsurf'`` :
      !    get value of Psurf from control parameter ``atm_fixed_Psurf``.
      !    get value of Tsurf from control parameter ``atm_fixed_Tsurf``.
      !    see the ``conductive_flame`` test_suite for an example of
      !    this boundary condition implemented via the ``other_surface_PT`` hook.

      ! ::

    atm_option = 'T_tau'


      ! atm_off_table_option
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If have selected ``'table'`` for ``atm_option``, fallback to using
      ! this if the args are off the table. Possible choices are ``'T_tau'``
      ! or blank (in which case the code will halt when it encounters an off-table
      ! arg)

      ! ::

    atm_off_table_option = 'T_tau'


      ! atm_fixed_Teff
      ! ~~~~~~~~~~~~~~

      ! Set this when using ``atm_option = 'fixed_Teff'``

      ! ::

    atm_fixed_Teff = 0


      ! atm_fixed_Tsurf
      ! ~~~~~~~~~~~~~~~

      ! Set this when using ``atm_option = 'fixed_Tsurf'``

      ! ::

    atm_fixed_Tsurf = 0


      ! atm_fixed_Psurf
      ! ~~~~~~~~~~~~~~~

      ! Set this when using ``atm_option = 'fixed_Psurf'``

      ! ::

    atm_fixed_Psurf = -1


      ! Pextra_factor
      ! ~~~~~~~~~~~~~

      ! Parameter for extra pressure in surface boundary conditions.
      ! Pressure at optical depth tau is calculated as ``P = tau*g/kap*(1 + Pextra)``
      ! Pextra takes into account nonzero radiation pressure at tau=0.
      ! The equation for Pextra includes ``Pextra_factor``

      ! ::

      !     Pextra = Pextra_factor*(kap/tau)*(L/M)/(6d0*pi*clight*cgrav)

      ! For certain situations such super eddington L,
      ! you may need to increase Pextra to help convergence.
      ! e.g. try ``Pextra_factor = 2``

      ! Note that ``Pextra_factor`` is only applied when ``atm_option`` = ``'T_tau'``
      ! and ``atm_T_tau_opacity`` = ``'fixed'`` or ``'iterated'``.

      ! ::

    Pextra_factor = 1


      ! atm_T_tau_relation
      ! ~~~~~~~~~~~~~~~~~~

      ! The T(tau) relation to use when ``atm_option`` = ``'T_tau'``

      ! + ``'Eddington'``:
      !   use the grey Eddington T(tau) relation.

      ! + ``'solar_Hopf'``:
      !   use a grey T(tau) relation with an approximate Hopf function tuned to
      !   solar data. See Paper II, Sec. A.5. Equivalent to the fit given by Sonoi
      !   et al. (2019, A&A, 621, 84) to the Vernazza et al. (1981) VAL-C model.

      ! + ``'Krishna_Swamy'``:
      !   use the grey T(tau) relation described by K.S. Krishna-Swamy, ApJ 145,
      !   174–194 (1966).

      ! + ``'Trampedach_solar'``:
      !   use the analytic fit by Ball (2021, RNAAS 5, 7) to the Hopf
      !   function for the solar simulation by Trampedach et al. (2014,
      !   MNRAS 442, 805–820)

      ! ::

    atm_T_tau_relation = 'Eddington'


      ! atm_T_tau_opacity
      ! ~~~~~~~~~~~~~~~~~

      ! Controls how opacities are calculated throughout the atmosphere when
      ! ``atm_option`` = ``'T_tau'``

      ! + ``'fixed'``:
      !   use a uniform opacity, fixed to the opacity of the outermost cell of the
      !   interior model

      ! + ``'iterated'``:
      !   use a uniform opacity, iterated to be consistent with the final Tsurf and
      !   Psurf at the base of the atmosphere.

      ! + ``'varying'``:
      !   use a varying opacity consistent with the local T and P throughout the
      !   atmosphere. Involves numerical integration of the hydrostatic equilibrium
      !   equation.

      ! ::

    atm_T_tau_opacity = 'fixed'


      ! atm_T_tau_errtol
      ! ~~~~~~~~~~~~~~~~

      ! Error tolerance for iterations and integrations when
      ! ``atm_option`` = ``'T_tau'`` and ``atm_T_tau_opacity`` = ``'iterated'`` or
      ! ``'varying'``.

      ! ::

    atm_T_tau_errtol = 1d-7


      ! atm_T_tau_max_iters
      ! ~~~~~~~~~~~~~~~~~~~

      ! Maximum number of iterations for the opacity when
      ! ``atm_option`` = ``'T_tau'`` and ``atm_T_tau_opacity`` = ``'iterated'``.

      ! ::

    atm_T_tau_max_iters = 50


      ! atm_T_tau_max_steps
      ! ~~~~~~~~~~~~~~~~~~~

      ! Maximum number of steps for integrating the hydrostatic equilibrium
      ! equation when ``atm_option`` = ``'T_tau'`` and ``atm_T_tau_opacity`` = ``'varying'``.

      ! ::

    atm_T_tau_max_steps = 500


      ! atm_table
      ! ~~~~~~~~~

      ! Determines which table Tsurf and Psurf are interpolated in

      ! + ``'tau_100'``, ``'tau_10'``, ``'tau_1'``, ``'tau_1m1'``:
      !   use model atmosphere tables for Pgas and T at tau=100, 10, 1
      !   or 0.1, respectively; solar Z only, as described in MESA Paper
      !   I (Paxton et al. 2011), Sec. 5.3.
      !   these tables are primarily for the evolution of low-mass
      !   stars, brown dwarfs, and giant planets.  They are constructed
      !   from Castelli & Kurucz (2003) for Teff > 3000 K and the COND
      !   model atmospheres (Allard et al. 2001) for Teff < 3000 K.
      !   where no published results are available, the table has been
      !   filled in using integration of the Eddington T(tau) relation

      ! + ``'photosphere'``:
      !   use model atmosphere tables for photosphere; range of Z's,
      !   as described in MESA Paper I (Paxton et al. 2011), Sec. 5.3.
      !   the tables cover log(Z/Zsun) from -4 to 0.5 for a GN93
      !   solar mixture, and span logg = -0.5 to 5.5 in steps of
      !   0.5 dex and Teff = 2000 to 50 000 K in steps of 250 K.
      !   they are constructed, in order of precedence, using the
      !   PHOENIX model atmospheres (Hauschildt et al. 1999a,b)
      !   and the models by Castelli & Kurucz (2003).  where
      !   neither is available, an entry is generated by
      !   integrating the Eddington T(tau) relation

      ! + ``'WD_tau_25'``:
      !   hydrogen atmosphere tables for cool white dwarfs
      !   giving Pgas and T at log10(tau) = 1.4 (tau = 25.11886)
      !   Teff goes from 40,000 K down to 2,000K with step of 100 K
      !   Log10(g) goes from 9.5 down to 5.5 with step of 0.1.
      !   R.D. Rohrmann, L.G. Althaus, and S.O. Kepler,
      !   Lyman α wing absorption in cool white dwarf stars,
      !   Mon. Not. R. Astron. Soc. 411, 781–791 (2011)

      ! + ``'DB_WD_tau_25'``:
      !   helium dominated (log(H/He)=-5.0) atmosphere tables for DB
      !   white dwarfs, provided by Odette Toloza and Detlev Koester.
      !   5000K < Teff < 40000K

      ! ::

    atm_table = 'tau_100'


      ! atm_irradiated_opacity
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Controls how thermal opacities are calculated throughout the atmosphere when
      ! ``atm_option`` = ``'irradiated_grey'``

      ! + ``'fixed'``:
      !   use a uniform opacity, fixed to the opacity of the outermost cell of the
      !   interior model.

      ! + ``'iterated'``:
      !   use a uniform opacity, iterated to be consistent with the final Tsurf and
      !   Psurf at the base of the atmosphere.

      ! ::

    atm_irradiated_opacity = 'fixed'


      ! atm_irradiated_errtol
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Error tolerance for iterations when ``atm_option`` = ``'irradiated_grey'``
      ! and ``atm_irradiated_opacity`` = ``'iterated'``.

      ! ::

    atm_irradiated_errtol = 1d-7


      ! atm_irradiated_max_iters
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! Maximum number of iterations for the opacity when ``atm_option`` =
      ! ``'irradiated_grey'`` and ``atm_irradiated_opacity`` = ``'iterated'``.

      ! ::

    atm_irradiated_max_iters = 50


      ! atm_irradiated_T_eq
      ! ~~~~~~~~~~~~~~~~~~~

      ! Equilibrium temperature based on irradiation.

      ! ::

      !     irrad_flux = Lstar/(4*pi*orbit**2)

      ! + Area of planet in plane perpendicular to ``irrad_flux = pi*Rplanet**2``.
      ! + Stellar luminosity received by ``planet = irrad_flux*area``.
      ! + This luminosity determines ``T_eq``:  ``T_eq**4 = irrad_flux/(4*sigma)``.

      ! ::

    atm_irradiated_T_eq = 100


      ! atm_irradiated_kap_v_div_kap_th
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! atm_irradiated_kap_v
      ! ~~~~~~~~~~~~~~~~~~~~

      ! The T(tau) relation when ``atm_option`` = ``'irradiated_grey'`` depends on the
      ! ratio ``kap_v/kap_th`` where ``kap_v`` is the planet atmosphere opacity for stellar
      ! irradiation, and ``kap_th`` is the thermal opacity for the internally produced
      ! radiation. There are two ways to calculate the ratio:
      !
      ! + if ``atm_irradiated_kap_v_div_kap_th`` > 0, then use it for ``kap_v/kap_th``
      !
      ! + if ``atm_irradiated_kap_v_div_kap_th`` == 0, then use ``atm_irradiated_kap_v``
      !   to set ``kap_v``, and then evaluate the ratio using ``kap_th``

      ! ::

    atm_irradiated_kap_v_div_kap_th = 0
    atm_irradiated_kap_v = 4d-3


      ! atm_irradiated_P_surf
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Surface pressure when ``atm_option`` = ``'irradiated_grey'``;
      ! default is 1 bar in cgs units.

      ! ::

    atm_irradiated_P_surf = 1d6


      ! use_compression_outer_BC
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! gradient of compression vanishes at surface

      !     see Grott, Chernigovski, Glatzel, 2005.
      !     d_dm(d_dm(r^2*v)) = 0 at surface
      !     by continuity, this is d_dm(d_dt(1/rho)) = 0 at surface
      !     finite volume form is
      !     (1/rho(1) - 1/rho_start(1)) = (1/rho(2) - 1/rho_start(2))
      !     this BC determines the density for surface cell.

      ! ::

    use_compression_outer_BC = .false.


      ! use_momentum_outer_BC
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! use ``P_surf`` from atm to set pressure gradient at surface in momentum equation
      ! calculate v(1) based on pressure difference ``P_surf - P(1)``

      ! ::

    use_momentum_outer_BC = .false.


      ! use_zero_Pgas_outer_BC
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! use ``Psurf = Radiation_Pressure(T_start(1))``

      ! ::

    use_zero_Pgas_outer_BC = .false.


      ! use_RSP_L_eqn_outer_BC
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! use RSP2 luminosity equation
      ! as the outer boundary condition on L rather than the
      ! default atmospheric BC for temperature.
      ! solves L1 - s% RSP2_Lsurf_factor*4*pi*r^2*c*a*T1^4 = 0
      ! uses dev control s% RSP2_Lsurf_factor  = 0.5 (default),
      ! see controls_dev.defaults.list

      ! ::

     use_RSP_L_eqn_outer_BC = .false.


      ! use_fixed_vsurf_outer_BC
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! fixed_vsurf
      ! ~~~~~~~~~~~

      ! v at outer boundary of model is set to be fixed_vsurf

      ! ::

    use_fixed_vsurf_outer_BC = .false.
    fixed_vsurf = 0


      ! use_fixed_Psurf_outer_BC
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! fixed_Psurf
      ! ~~~~~~~~~~~

      ! P at outer boundary of model is set to be fixed_Psurf

      ! ::

    use_fixed_Psurf_outer_BC = .false.
    fixed_Psurf = 0

      ! irradiation_flux
      ! ~~~~~~~~~~~~~~~~
      ! column_depth_for_irradiation
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    irradiation_flux = 0
    column_depth_for_irradiation = -1


      ! atm_build_tau_outer
      ! ~~~~~~~~~~~~~~~~~~~
      ! atm_build_dlogtau
      ! ~~~~~~~~~~~~~~~~~
      ! atm_build_errtol
      ! ~~~~~~~~~~~~~~~~

      ! Parameters controlling atmosphere structure building. MESA can
      ! evaluate the spatial structure of the atmosphere for the
      ! following ``atm_option`` choice:

      ! + ``'T_tau'``

      ! The atmosphere structure data are appended to the interior model
      ! when ``add_atmosphere_to_pulsation = .true.``. They do not affect
      ! the surface boundary conditions applied to the interior model.

      ! ``atm_build_tau_outer`` specifies the outermost optical depth to
      ! include in the atmosphere; ``atm_build_dlntau`` specifies the
      ! spacing of atmosphere points in (base-10) logarithmic optical depth;
      ! and ``atm_build_errtol`` specifies the error tolerance for evaluating
      ! the structure.

      ! ::

    atm_build_tau_outer = 1d-3
    atm_build_dlogtau = 0.01
    atm_build_errtol = 1d-8


      ! use_T_tau_gradr_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! If ``.true.``, modify the radiative gradient so that the
      ! temperature profile of the optically thin layers follow the
      ! T(τ) relation chosen by ``atm_T_tau_relation``.
      ! ::

    use_T_tau_gradr_factor = .false.


! starspots
! =========


      ! do_starspots
      ! ~~~~~~~~~~~~

      ! If ``.true.``, switch on impedance of the surface flux due to magnetic pressure from starspots,
      ! parameterized in the style of an atmospheric boundary modification. First described by
      ! `Somers et al. (2015) <https://ui.adsabs.harvard.edu/abs/2015ApJ...807..174S>`_.
      ! Detailed discussion of this functionality can be found in |MESA VI|.

      ! ::

    do_starspots = .false.


      ! fspot
      ! ~~~~~

      ! Filling Factor of starspots. Valid values between 0.0 and 1.0 (no spots to 100% coverage)
      ! ::

    fspot = 0d0


      ! xspot
      ! ~~~~~

      ! Temperature contrast between the spotted and unspotted regions.
      ! Valid values are between 1.0 (no contribution from magnetic pressure) and 0.5
      ! (half of the total pressure is due to magnetic pressure)

      ! ::

    xspot = 1d0


! mass gain or loss
! =================


      ! mass_change
      ! ~~~~~~~~~~~

      ! Rate of accretion (Msun/year). Negative for mass loss.
      ! This only applies when the ``wind_scheme = ''``.

      ! ::

    mass_change = 0d0


      ! mdot_omega_power
      ! ~~~~~~~~~~~~~~~~

      ! Enhanced mass loss due to rotation
      ! as in Heger, Langer, and Woosley, 2000, ApJ, 528:368-396.

      !      Mdot = Mdot_no_rotation/(1 - Osurf/Osurf_crit)^mdot_omega_power

      ! where

      !     Osurf = angular velocity at surface
      !     Osurf_crit^2 = (1 - Gamma_edd)*G*M/R^3
      !     Gamma_edd = kappa*L/(4 pi c G M), Eddington factor

      ! Typical value for ``mdot_omega_power = 0.43``.

      ! Set to 0 to disable this feature.

      ! ::

    mdot_omega_power = 0.43d0


      ! max_rotational_mdot_boost
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! This limits the rotational boost.

      ! ::

    max_rotational_mdot_boost = 1d4


      ! max_mdot_jump_for_rotation
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Don't increase prev mdot by more that this.

      ! ::

    max_mdot_jump_for_rotation = 2


      ! lim_trace_rotational_mdot_boost
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Output to terminal if boost > this.

      ! ::

    lim_trace_rotational_mdot_boost = 1d99


      ! rotational_mdot_boost_fac
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Increase mdot.

      ! ::

    rotational_mdot_boost_fac = 1d5


      ! rotational_mdot_kh_fac
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Kelvin-helmholtz boost.

      ! ::

    rotational_mdot_kh_fac = 0.3d0


      ! surf_avg_tau_min
      ! ~~~~~~~~~~~~~~~~

      ! Use mass avg starting from this optical depth.

      ! ::

    surf_avg_tau_min = 1


      ! surf_avg_tau
      ! ~~~~~~~~~~~~

      ! Use mass avg down to this optical depth.

      ! ::

    surf_avg_tau = 100


      ! hot_wind_scheme
      ! ~~~~~~~~~~~~~~~
      ! cool_wind_RGB_scheme
      ! ~~~~~~~~~~~~~~~~~~~~
      ! cool_wind_AGB_scheme
      ! ~~~~~~~~~~~~~~~~~~~~

      ! This section replaces the old "``RGB_wind_scheme``" and "``AGB_wind_scheme``"
      ! with temperature-dependent hot\_wind and cool\_wind. You can still
      ! use the RGB and AGB wind scheme as before, the functionality remains.

      ! Now you can also select a hot wind scheme that takes effect *above*
      ! some temperature, set by ``hot_wind_full_on_T``.
      ! Similarly, the cool wind scheme has temperature controls that
      ! set the temperature *below* which they are relevant (``cool_wind_full_on_T``).

      ! As before, an empty string '' means no wind.

      ! The wind "eta" values, which are constant scaling factors, have all
      ! renamed \*\_wind\_eta -> \*\_scaling\_factor.

      ! Here is an example of how to translate an existing inlist from the
      ! old style to the new:

      !     +----------------------------------+-----------------------------------+
      !     |        Before                    |             After                 |
      !     +==================================+===================================+
      !     | RGB_wind_scheme = 'Reimers'      |  cool_wind_RGB_scheme = 'Reimers' |
      !     | Reimers_wind_eta = 0.1           |  Reimers_scaling_factor = 0.1     |
      !     | AGB_wind_scheme = 'Blocker'      |  cool_wind_AGB_scheme = 'Blocker' |
      !     | Blocker_wind_eta = 0.5           |  Blocker_scaling_factor = 0.5     |
      !     | RGB_to_AGB_wind_switch = 1d-4    |  RGB_to_AGB_wind_switch = 1d-4    |
      !     |                                  |                                   |
      !     |                                  |  ! only use the cool_wind_scheme  |
      !     |                                  |  cool_wind_full_on_T = 1d10  !K   |
      !     |                                  |  hot_wind_full_on_T = 1.1d10 !K   |
      !     |                                  |  hot_wind_scheme = ''             |
      !     +----------------------------------+-----------------------------------+

      ! suggested hot and cool wind schemes follow but any valid wind option
      ! will work for either hot or cool.

      ! Empty string means no wind

      ! Suggested hot wind option:

      !   + 'Vink'
      !   + 'Bjorklund'

      ! Suggested cool wind options:

      !   + 'Reimers'
      !   + 'Blöcker'
      !   + 'de Jager'
      !   + 'van Loon'
      !   + 'Nieuwenhuijzen'

      ! For now the 'Dutch' scheme can be used in either capacity.

      ! NOTE: for schemes that scale with metallicitity, we use Zbase rather than Z (as long as Zbase > 0).
      ! This is because wind mass loss rate is primarily determined by iron opacity,
      ! which is unlikely to change during the evolution.

      ! ::

    hot_wind_scheme = ''
    cool_wind_RGB_scheme = ''
    cool_wind_AGB_scheme = ''


      ! cool_wind_full_on_T
      ! ~~~~~~~~~~~~~~~~~~~
      ! hot_wind_full_on_T
      ! ~~~~~~~~~~~~~~~~~~

      ! NOTE: hot_wind_full_on_T was previously called 'cool_wind_full_off_T'

      ! use only cool wind schemes for T\_phot < ``cool_wind_full_on_T``
      ! use only hot wind schemes for T\_phot > ``hot_wind_full_on_T``
      ! if ``cool_wind_full_on_T`` /= ``hot_wind_full_on_T`` then ramp between these limits
      ! requires ``hot_wind_full_on_T`` > ``cool_wind_full_on_T``

      ! ::

    cool_wind_full_on_T = 0.8d4
    hot_wind_full_on_T = 1.2d4


      ! RGB_to_AGB_wind_switch
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! If center hydrogen abundance is < 0.01
      ! and center helium abundance by mass is less than ``RGB_to_AGB_wind_switch``,
      ! then system will use ``AGB_wind_scheme`` rather than ``RGB_wind_scheme``.

      ! ::

    RGB_to_AGB_wind_switch = 1d-4

      ! The code will automatically choose between an RGB wind and an AGB wind.
      ! The following names for the different schemes are recognized:

      ! + 'Reimers'
      ! + 'Blocker'
      ! + 'de Jager'
      ! + 'van Loon'
      ! + 'Nieuwenhuijzen'
      ! + 'Vink'
      ! + 'Dutch'
      ! + 'Bjorklund'
      ! + 'other'  --- for wind options implemented using other_wind hook


      ! Reimers_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Reimers mass loss for red giants.

      ! D. Reimers
      ! "Problems in Stellar Atmospheres and Envelopes"
      ! Baschek, Kegel, Traving (eds), Springer, Berlin, 1975, p. 229.

      ! Parameter for mass loss by Reimers wind prescription.
      ! Reimers mdot is ``eta*4d-13*L*R/M`` (Msun/year), with L, R, and M in solar units.
      ! Typical value is 0.5.

      ! ::

    Reimers_scaling_factor = 0


      ! Blocker_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Blocker's mass loss for AGB stars.

      ! T. Blocker
      ! "Stellar evolution of low and intermediate-mass stars"
      ! A&A 297, 727-738 (1995).

      ! Parameter for mass loss by Blocker's wind prescription.
      ! Blocker mdot is ``eta*4.83d-9*M**-2.1*L**2.7*4d-13*L*R/M`` (Msun/year),
      ! with L, R, and M in solar units.
      ! Typical value is 0.1d0.

      ! ::

    Blocker_scaling_factor = 0


      ! de_Jager_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! de Jager mass loss for various applications.
      ! de Jager, C., Nieuwenhuijzen, H., & van der Hucht, K. A. 1988, A&AS, 72, 259.
      ! Parameter for mass loss by de Jager wind prescription.

      ! ::

    de_Jager_scaling_factor = 0d0


      ! van_Loon_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! see van Loon et al. 2005, A&A, 438, 273
      ! "An empirical formula for the mass-loss rates of dust-enshrouded
      ! red supergiants and oxygen-rich Asymptotic Giant Branch stars"

      ! ::

    van_Loon_scaling_factor = 0d0


      ! Nieuwenhuijzen_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! See Nieuwenhuijzen, H.; de Jager, C. 1990, A&A, 231, 134.

      ! ::

    Nieuwenhuijzen_scaling_factor = 0d0


      ! Vink_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~~

      ! Vink, J.S., de Koter, A., & Lamers, H.J.G.L.M., 2001, A&A, 369, 574.
      ! "Mass-loss predictions for O and B stars as a function of metallicity"

      ! ::

    Vink_scaling_factor = 0d0

      ! Bjorklund_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! Björklund, R., Sundqvist, J.O., Puls, J., & Najarro, F., 2021, A&A, 648, A36.
      ! "New predictions for radiation-driven, steady-state mass-loss and
      ! wind-momentum from hot, massive stars II.
      ! A grid of O-type stars in the Galaxy and the Magellanic Clouds"

      ! This wind scheme does not feature a bistability jump.

   Bjorklund_scaling_factor = 0d0

      ! Dutch_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~~~

      ! The "Dutch" wind scheme for massive stars combines results from several papers,
      ! all with authors mostly from the Netherlands.

      ! The particular combination we use is based on
      ! Glebbeek, E., et al, A&A 497, 255-264 (2009) [more Dutch authors!]

      ! For Teff > 1e4 and surface H > 0.4 by mass, use Vink et al 2001
      ! Vink, J.S., de Koter, A., & Lamers, H.J.G.L.M., 2001, A&A, 369, 574.

      ! For Teff > 1e4 and surface H < 0.4 by mass, use Nugis & Lamers 2000
      ! Nugis, T.,& Lamers, H.J.G.L.M., 2000, A&A, 360, 227
      ! Some folks use 0.8 for non-rotating models (Maeder & Meynet, 2001).

      ! ::

    Dutch_scaling_factor = 0d0


      ! Dutch_wind_lowT_scheme
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! For Teff < 1e4

      ! Use de Jager if ``Dutch_wind_lowT_scheme = 'de Jager'``
      ! de Jager, C., Nieuwenhuijzen, H., & van der Hucht, K. A. 1988, A&AS, 72, 259.

      ! Use van Loon if ``Dutch_wind_lowT_scheme = 'van Loon'``
      ! van Loon et al. 2005, A&A, 438, 273.

      ! Use Nieuwenhuijzen if ``Dutch_wind_lowT_scheme = 'Nieuwenhuijzen'``
      ! Nieuwenhuijzen, H.; de Jager, C. 1990, A&A, 231, 134

      ! ::

    Dutch_wind_lowT_scheme = 'de Jager'


      ! Kudritzki_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! Radiation driven winds of hot stars.
      ! See Kudritzki et al, Astron. Astrophys. 219, 205-218 (1989).
      ! this is now implemented using the other_wind hook.  See other_physics_hooks test case.


      ! Grafener_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Grafener, G. & Hamann, W.-R. 2008, A&A 482, 945
      ! contributed to mesa by Nilou Afsari
      ! this is now implemented using the other_wind hook.  see other_physics_hooks test case.


      ! Stern51_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! this is now implemented using the other_wind hook.  see other_physics_hooks test case.


      ! use_accreted_material_j
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! accreted_material_j
      ! ~~~~~~~~~~~~~~~~~~~

      ! Angular momentum of accreted material.

      ! ::

    use_accreted_material_j = .false.

      ! If false, then accreted material is given j so that it
      ! is rotating at the same angular velocity as the surface.
      ! If true, then accreted material is given j = ``accreted_material_j``.

      ! ::

    accreted_material_j = 0


      ! no_wind_if_no_rotation
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Use this to delay start of wind until after have started rotation.

      ! ::

    no_wind_if_no_rotation = .false.


      ! min_wind
      ! ~~~~~~~~

      ! Min wind in Msun/year > 0; ignore this limit if it is <= 0.
      ! e.g., might have low level wind even when normal scheme doesn't call for any.

      ! ::

    min_wind = 0d0


      ! max_wind
      ! ~~~~~~~~

      ! Max wind in Msun/year > 0; ignore this limit if it is <= 0.

      ! ::

    max_wind = 0d0

      ! For critical rotation mass loss
      ! Redo step as needed to find mdot that brings model to just below critical.
      ! if ``max_mdot_redo_cnt`` > 0, and ``surf_omega_div_omega_crit`` > ``surf_omega_div_omega_crit_limit``,
      ! then recompute the step while increasing mdot, until
      ! ``surf_omega_div_omega_crit`` < ``surf_omega_div_omega_crit_limit``. Once an upper limit for mdot is found,
      ! the solution for mdot is further refined by bisection until it is computed to a tolerance of
      ! ``surf_omega_div_omega_crit_tol``. During iterations, mdot is adjusted alternately by multiplication
      ! by ``mdot_revise_factor``, and by adjusting it by ``implicit_mdot_boost*mdot_initial``, where
      ! ``mdot_initial`` is the value of mdot at the first iteration. This is done to deal with mass
      ! accreting stars, where mdot might need to change sign for the star to remain below critical.
      ! This is a direct replacement for ``surf_w_div_w_crit_limit`` and ``surf_w_div_w_crit_tol``

      ! ::

    max_mdot_redo_cnt = 0
    min_years_dt_for_redo_mdot = 0
    surf_omega_div_omega_crit_limit = 0.99d0
    surf_omega_div_omega_crit_tol = 0.05d0
    mdot_revise_factor = 1.1d0
    implicit_mdot_boost = 0.1d0


   ! implicit wind computation.
   ! __________________________


      ! max_tries_for_implicit_wind
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! The implicit method will modify the mass transfer rate and redo the step until
      ! it either finds a solution, or the number of tries hits ``max_tries_for_implicit_wind``.
      ! If ``max_tries_for_implicit_wind = 0``, the wind computation is explicit,
      ! meaning that the value of mdot is set using values at the start of the step.
      ! This only applies when mdot < 0.

      ! ::

    max_tries_for_implicit_wind = 0


      ! iwind_tolerance
      ! ~~~~~~~~~~~~~~~

      ! Tolerance for which a solution is considered valid.
      ! A solution is valid if

      ! ::

      !     abs(explicit_mdot - implicit_mdot) <
      !            abs(implicit_mdot)*iwind_tolerance

      ! where

      ! ::

      !     explicit_mdot = mstar_dot at start of step
      !     implicit_mdot = mstar_dot at end of step

      ! ::

    iwind_tolerance = 1d-3


      ! iwind_lambda
      ! ~~~~~~~~~~~~

      ! If do not satisfy tolerance, redo with a different mdot as follows:
      !
      !         mstar_dot = explicit_mdot + &
      !            iwind_lambda*(implicit_mdot - explicit_mdot)

      ! ::

    iwind_lambda = 1d0


      ! super_eddington_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! For super eddington wind we use Ledd averaged by mass to optical depth tau = ``surf_avg_tau``.

      ! ::

    super_eddington_scaling_factor = 0


      ! super_eddington_wind_Ledd_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Parameter for mass loss driven by super Eddington luminosity.
      ! Divide L by this factor when computing super Eddington wind,
      ! e.g., if this is 2, then only get wind when L/2 > Ledd.

      ! ::

    super_eddington_wind_Ledd_factor = 1


      ! wind_boost_full_off_L_div_Ledd
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Boost off for L/Ledd <= this (set large to disable this).
      ! This alternative form is used when ``super_eddington_scaling_factor`` == 0.

      ! ::

    wind_boost_full_off_L_div_Ledd = 1.5d0


      ! wind_boost_full_on_L_div_Ledd
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Do max boost for L/Ledd >= this.
      ! This alternative form is used when ``super_eddington_scaling_factor`` == 0.

      ! ::

    wind_boost_full_on_L_div_Ledd = 5


      ! super_eddington_wind_max_boost
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Multiply wind mdot by up to this amount.
      ! This alternative form is used when ``super_eddington_scaling_factor`` == 0.

      ! ::

    super_eddington_wind_max_boost = 1


      ! trace_super_eddington_wind_boost
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Send super eddington wind information to terminal.

      ! ::

    trace_super_eddington_wind_boost = .false.


      ! mass_change_full_on_dt
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! mass_change_full_off_dt
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! These params provide the option to turn off mass change when have very small timesteps.
      ! Between ``mass_change_full_on_dt`` and ``mass_change_full_off_dt`` mass change is gradually reduced.
      ! Units in seconds.

      ! ::

    mass_change_full_on_dt = 1d-99
    mass_change_full_off_dt = 1d-99


      ! trace_dt_control_mass_change
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    trace_dt_control_mass_change = .false.


      ! max_star_mass_for_gain
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Automatic stops for mass loss/gain
      ! in Msun units (negative means ignore this parameter).
      ! Turn off mass gain when star mass reaches this limit.

      ! ::

    max_star_mass_for_gain = -1


      ! min_star_mass_for_loss
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Automatic stops for mass loss/gain
      ! in Msun units (negative means ignore this parameter).
      ! Turn off mass loss when star mass reaches this limit.

      ! ::

    min_star_mass_for_loss = -1


      ! max_T_center_for_any_mass_loss
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! No mass loss for T center > this.

      ! ::

    max_T_center_for_any_mass_loss = 2d9


      ! max_T_center_for_full_mass_loss
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! No reduction in mass loss for T center <= this.
      ! This must be <= ``max_T_center_for_full_mass_loss``.
      ! Reduce mass loss rate to 0 as T center climbs from ``max_for_full`` to ``max_for_any``.
      ! The idea behind this is that during final stages of burning, there is so little time
      ! left in the life of the star, that any mass loss to winds will be negligible,
      ! but the inclusion of that insignificant mass loss can actually make
      ! convergence more difficult, so you are better off without it.

      ! ::

    max_T_center_for_full_mass_loss = 1d9


      ! wind_H_envelope_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Winds automatically shut off when star_mass - he_core_mass mass is less than this limit.
      ! The value of ``he_core_boundary_h1_fraction`` defines he_core_mass.
      ! Mass in Msun units. Previously called ``wind_envelope_limit``.

      ! ::

    wind_H_envelope_limit = -1


      ! wind_H_He_envelope_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! Winds automatically shut off when star_mass - co_core_mass is less than this limit.
      ! The value of ``co_core_boundary_he4_fraction`` defines co_core_mass.
      ! Mass in Msun units.

      ! ::

    wind_H_He_envelope_limit = -1


      ! wind_He_layer_limit
      ! ~~~~~~~~~~~~~~~~~~~

      ! Winds automatically shut off when he_core_mass - co_core_mass is less than this limit.
      ! Mass in Msun units.

      ! ::

    wind_He_layer_limit = -1


      ! rlo_scaling_factor
      ! ~~~~~~~~~~~~~~~~~~

      ! Amplitude of mass loss.
      ! "rlo" wind scheme provides a simple radius-determined-wind with exponential increase.

      ! ::

    rlo_scaling_factor = 0


      ! rlo_wind_min_L
      ! ~~~~~~~~~~~~~~

      ! Only on when L > this limit. (Lsun)

      ! ::

    rlo_wind_min_L = 1d-6


      ! rlo_wind_max_Teff
      ! ~~~~~~~~~~~~~~~~~

      ! Only on when Teff < this limit.

      ! ::

    rlo_wind_max_Teff = 1d99


      ! rlo_wind_roche_lobe_radius
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Only on when R > this (Rsun).

      ! ::

    rlo_wind_roche_lobe_radius = 0.40d0


      ! rlo_wind_base_mdot
      ! ~~~~~~~~~~~~~~~~~~

      ! Base rate of mass loss when R = roche lobe radius (Msun/year).

      ! ::

    rlo_wind_base_mdot = 1d-3


      ! rlo_wind_scale_height
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Determines exponential growth rate of mass loss (Rsun).

      ! ::

    rlo_wind_scale_height = 1d-1


      ! roche_lobe_xfer_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Full accretion when R/RL <= this.
      ! Limit accretion when Roche lobe is nearing full (only with ``rlo_scaling_factor`` > 0).

      ! ::

    roche_lobe_xfer_full_on = 0.5d0


      ! roche_lobe_xfer_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! No accretion when R/RL >= this.

      ! ::

    roche_lobe_xfer_full_off = 1.0d0


   ! controls for adjust_mass
   ! ________________________


      ! max_logT_for_k_below_const_q
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_q_for_k_below_const_q
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_q_for_k_below_const_q
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Move ``k_below_const_q`` inward from surface until ``q(k) <= max_q``.
      ! Then continue moving inward until reach ``logT(k) >= max_logT`` or ``q(k) <= min_q``.

      ! ::

    max_logT_for_k_below_const_q = 5
    max_q_for_k_below_const_q = 1.0d0
    min_q_for_k_below_const_q = 0.999d0


      ! max_logT_for_k_const_mass
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_q_for_k_const_mass
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! min_q_for_k_const_mass
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Move ``k_const_mass`` inward from ``k_below_const_q+1`` until ``q(k) <= max_q``.
      ! Then continue moving inward until reach ``logT(k) >= max_logT`` or ``q(k) <= min_q``.

      ! ::

    max_logT_for_k_const_mass = 6
    max_q_for_k_const_mass = 1.0d0
    min_q_for_k_const_mass = 0.995d0

! composition controls
! ====================


      ! accrete_same_as_surface
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, composition of accreted material is identical to the current surface composition.
      ! If false, then the composition is determined by ``accrete_given_mass_fractions``.

      ! The actual mass accretion rate can be set up using the ``mass_change`` option.

      ! ::

    accrete_same_as_surface = .true.


      ! accrete_given_mass_fractions
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, use ``accrete_given_mass_fractions``, ``num_accretion_species``,
      ! ``accretion_species_id`` and ``accretion_species_xa`` to determine composition
      ! of accreted material -- they must add to 1.0.

      ! If false, then the composition is determined using ``accretion_h1``, ``accretion_h2``,
      ! ``accretion_he3``, ``accretion_he4`` and ``accretion_zfracs``.

      ! The actual mass accretion rate can be set up using the ``mass_change`` option.

      ! Note that this control is ignored if ``accrete_same_as_surface`` is true.

      ! ::

    accrete_given_mass_fractions = .false.


      ! num_accretion_species
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! accretion_species_id
      ! ~~~~~~~~~~~~~~~~~~~~
      ! accretion_species_xa
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If accrete_same_as_surface is false and accrete_given_mass_fractions is true,
      ! then composition of accreted material is determined by these options.
      ! The actual mass accretion rate can be set up using the ``mass_change`` option.

      ! ``num_accretion_species`` can be up to ``s% max_num_accretion_species``, see
      ! ``star/public/star_def.inc`` for the value of this parameter.

      ! For each of ``num_accretion_species``, the id for the isotope needs to be specified
      ! by ``accretion_species_id`` as defined in ``chem/public/chem_def.f90``.

      ! Mass fractions for each isotope are defined by ``accretion_species_xa``

      ! ::

    num_accretion_species = 0
    accretion_species_id(1) = ''
    accretion_species_xa(1) = 0


      ! accretion_h1
      ! ~~~~~~~~~~~~
      ! accretion_h2
      ! ~~~~~~~~~~~~
      ! accretion_he3
      ! ~~~~~~~~~~~~~
      ! accretion_he4
      ! ~~~~~~~~~~~~~

      ! If accrete_same_as_surface is false and accrete_given_mass_fractions is false,
      ! then the mass fractions of h1, h2, he3 and h4 are determined by these options.
      ! Mass fractions for metals are set with the ``accretion_zfracs`` control.
      ! The actual mass accretion rate can be set up using the ``mass_change`` option.

      ! If no h2 in current net, then it is automatically added to h1.

      ! ::

    accretion_h1 = 0
    accretion_h2 = 0
    accretion_he3 = 0
    accretion_he4 = 0


      ! accretion_zfracs
      ! ~~~~~~~~~~~~~~~~

      ! One of the following identifiers for different Z fractions from ``chem_def``.

      ! + ``AG89_zfracs = 1``, Anders & Grevesse 1989
      ! + ``GN93_zfracs = 2``, Grevesse & Noels 1993
      ! + ``GS98_zfracs = 3``, Grevesse & Sauval 1998
      ! + ``L03_zfracs = 4``, Lodders 2003
      ! + ``AGS05_zfracs = 5``, Asplund, Grevesse & Sauval 2005

      ! or set ``accretion_zfracs = 0`` to use the following list of z fractions

      ! ::

    accretion_zfracs = -1


      ! accretion_dump_missing_metals_into_heaviest
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! this controls the treatment metals that are not included in the current net.
      ! if this flag is true, then the mass fractions of missing metals are added
      ! to the mass fraction of the most massive metal included in the net.
      ! if this flag is false, then the mass fractions of the metals in the net
      ! are renormalized to make up for the total mass fraction of missing metals.

      ! ::

    accretion_dump_missing_metals_into_heaviest = .true.

      ! Special list of z fractions.
      ! If you use these, they must add to 1.0.

      ! ::

    z_fraction_li = 0
    z_fraction_be = 0
    z_fraction_b = 0
    z_fraction_c = 0
    z_fraction_n = 0
    z_fraction_o = 0
    z_fraction_f = 0
    z_fraction_ne = 0
    z_fraction_na = 0
    z_fraction_mg = 0
    z_fraction_al = 0
    z_fraction_si = 0
    z_fraction_p = 0
    z_fraction_s = 0
    z_fraction_cl = 0
    z_fraction_ar = 0
    z_fraction_k = 0
    z_fraction_ca = 0
    z_fraction_sc = 0
    z_fraction_ti = 0
    z_fraction_v = 0
    z_fraction_cr = 0
    z_fraction_mn = 0
    z_fraction_fe = 0
    z_fraction_co = 0
    z_fraction_ni = 0
    z_fraction_cu = 0
    z_fraction_zn = 0


      ! lgT_lo_for_set_new_abundances
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! lgT_hi_for_set_new_abundances
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Composition controls for ``set_new_abundances``.

      ! ::

    lgT_lo_for_set_new_abundances = 5.2d0
    lgT_hi_for_set_new_abundances = 5.5d0

! mesh adjustment
! ===============


      ! max_allowed_nz
      ! ~~~~~~~~~~~~~~

      ! Maximum number of grid points allowed.
      ! Array allowed to grow arbitrarily large if max_allowed_nz <= 0
      ! If nz > max_allowed_nz, MESA will prematurely exit and call this error.

      ! ::

    max_allowed_nz = 8000


      ! remesh_max_allowed_logT
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Turn off remesh if any cell has logT > this.

      ! ::

    remesh_max_allowed_logT = 1d99


      ! mesh_max_allowed_ratio
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Must be >= 2.5.
      ! Max ratio for mass of adjacent cells.
      ! If have ratio exceeding this, split the larger cell.

      ! ::

    mesh_max_allowed_ratio = 2.5d0


      ! max_delta_x_for_merge
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Don't merge neighboring cells if any abundance differs by more than this.

      ! ::

    max_delta_x_for_merge = 0.1d0


      ! mesh_delta_coeff
      ! ~~~~~~~~~~~~~~~~

      ! A larger value increases the max allowed deltas and decreases the number of grid points.
      ! and a smaller does the opposite.

      ! analogous to time_delta_coeff for better time resolution.

      ! E.g., you'll roughly double the number of grid points if you cut ``mesh_delta_coeff`` in half.
      ! Don't expect it to exactly double the number however since other parameters in addition to
      ! gradients also influence the details of the grid spacing.

      ! this factor also applies to max_dq, max_center_cell_dq, and max_surface_cell_dq.

      ! ::

    mesh_delta_coeff = 1.0d0


      ! mesh_Pgas_div_P_exponent
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! Multiply ``mesh_delta_coeff`` by (Pgas/Ptotal) to this power.

      ! ::

    mesh_Pgas_div_P_exponent = 0


      ! mesh_delta_coeff_for_highT
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Use different ``mesh_delta_coeff`` at higher temperatures.

      ! ::

    mesh_delta_coeff_for_highT = 3.0d0


      ! logT_max_for_standard_mesh_delta_coeff
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Use ``mesh_delta_coeff`` for center logT <= this.  This value
      ! should be less than ``logT_min_for_highT_mesh_delta_coeff``.

      ! ::

    logT_max_for_standard_mesh_delta_coeff = 9.0d0


      ! logT_min_for_highT_mesh_delta_coeff
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Use ``mesh_delta_coeff_for_highT`` for center logT >= this.
      ! Linearly interpolate in logT for intermediate center temperatures.

      ! ::

    logT_min_for_highT_mesh_delta_coeff = 9.5d0


      ! max_dq
      ! ~~~~~~

      ! Max size for cell as fraction of total mass.

      ! ::

    max_dq = 1d-2


      ! min_dq
      ! ~~~~~~

      ! Min size for cell as fraction of total mass.

      ! ::

    min_dq = 1d-14

      ! min_dq_for_split
      ! ~~~~~~~~~~~~~~~~

      ! Min size for cell to be split.

      ! ::

    min_dq_for_split = 1d-14


      ! min_dq_for_xa
      ! ~~~~~~~~~~~~~

      ! Min size for splitting because of composition gradient.
      ! only for non-convective regions if have set min_dq_for_xa_convective > 0.

      ! ::

    min_dq_for_xa = 1d-14


      ! min_dq_for_xa_convective
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! Min size for splitting because of composition gradient in convective regions.
      ! if <= 0, then use min_dq_for_xa instead of this.

      ! ::

    min_dq_for_xa_convective = 1d-6

      ! min_dq_for_log_T
      ! ~~~~~~~~~~~~~~~~

      ! Min size for cell to be split because of jump in logT.

      ! ::

    min_dq_for_logT = 1d-14


      ! mesh_min_dlnR
      ! ~~~~~~~~~~~~~

      ! Limit on difference in lnR across cell for mesh refinement.
      ! Do not make this smaller than about 1d-14 or will fail with numerical problems.

      ! ::

    mesh_min_dlnR = 1d-9


      ! merge_if_dlnR_too_small
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, mesh adjustment will force merge if difference in lnR across cell is too small.

      ! ::

    merge_if_dlnR_too_small = .false.


      ! mesh_min_dr_div_dRstar
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Limit on relative radial extent for mesh refinement.
      ! dRstar = s% r(1) - s% R_center
      ! Don't split if dr/dRstar would drop below this limit.

      ! ::

    mesh_min_dr_div_dRstar = -1


      ! merge_if_dr_div_dRstar_too_small
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, mesh adjustment will force merge if ``dr_div_dRstar`` too small.

      ! ::

    merge_if_dr_div_dRstar_too_small = .true.


      ! mesh_min_dr_div_cs
      ! ~~~~~~~~~~~~~~~~~~

      ! Limit (in seconds) on sound crossing time for mesh refinement.
      ! Don't split if sound crossing time would drop below this limit.

      ! ::

    mesh_min_dr_div_cs = -1


      ! merge_if_dr_div_cs_too_small
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, mesh adjustment will force merge if ``dr_div_cs`` too small.

      ! ::

    merge_if_dr_div_cs_too_small = .true.


      ! max_center_cell_dq
      ! ~~~~~~~~~~~~~~~~~~

      ! Largest allowed dq at center.

      ! ::

    max_center_cell_dq = 1d-7


      ! max_surface_cell_dq
      ! ~~~~~~~~~~~~~~~~~~~

      ! min_surface_cell_dq
      ! ~~~~~~~~~~~~~~~~~~~

      ! Largest allowed dq at surface.

      ! ::

    max_surface_cell_dq = 1d-12
    min_surface_cell_dq = 1d-99


      ! max_num_subcells
      ! ~~~~~~~~~~~~~~~~

      ! Limits number of new cells from 1 old one.

      ! ::

    max_num_subcells = 2


      ! max_num_merge_cells
      ! ~~~~~~~~~~~~~~~~~~~
      ! max_num_merge_surface_cells
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Limits number of old cells to merge into 1 new one.

      ! ::

    max_num_merge_cells = 2
    max_num_merge_surface_cells = 2


      ! mesh_adjust_get_T_from_E
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, then use internal energy conservation to set new temperature.
      ! If false, just use average temperature based on reconstruction polynomials.

      ! ::

    mesh_adjust_get_T_from_E = .true.


      ! mesh_ok_to_merge
      ! ~~~~~~~~~~~~~~~~
      ! mesh_max_k_old_for_split
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! mesh_min_k_old_for_split
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    mesh_ok_to_merge = .true.
    mesh_max_k_old_for_split = 999999999
    mesh_min_k_old_for_split = 0


      ! E_function_weight
      ! ~~~~~~~~~~~~~~~~~
      ! E_function_param
      ! ~~~~~~~~~~~~~~~~

      ! internal energy gradient, ``E_function = E_function_weight*max(E_function_param,log10(energy))``.

      ! ::

    E_function_weight = 0
    E_function_param = 16d0


      ! P_function_weight
      ! ~~~~~~~~~~~~~~~~~

      ! Pressure gradient, ``P_function = P_function_weight*log10(P)``.

      ! ::

    P_function_weight = 40


      ! T_function1_weight
      ! ~~~~~~~~~~~~~~~~~~

      ! Temperature gradient, ``T_function1 = T_function1_weight*log10(T)``.
      ! NOTE: The T gradient mesh controls below seems to be necessary to allow burning that starts off center
      ! to be able to reach the center. You can see this in the ``pre_zahb`` ``test_suite`` case if you
      ! try running it without the T function. The center temperature will fail to rise.

      ! ::

    T_function1_weight = 110


      ! T_function2_weight
      ! ~~~~~~~~~~~~~~~~~~
      ! T_function2_param
      ! ~~~~~~~~~~~~~~~~~

      ! ::

      !     T_function2 = T_function2_weight*log10(T / (T + T_function2_param))

      ! Largest change in ``T_function2`` happens around ``T = T_function2_param``.
      ! Default value puts this in the envelope ionization region.

      ! ::

    T_function2_weight = 0
    T_function2_param = 2d4


      ! R_function_weight
      ! ~~~~~~~~~~~~~~~~~
      ! R_function_param
      ! ~~~~~~~~~~~~~~~~

      ! log radius gradient

      ! ::

      !     R_function = R_function_weight*log10(1 + (r/Rsun)/R_function_param)

      ! ::

    R_function_weight = 0
    R_function_param = 1d-4


      ! R_function2_weight
      ! ~~~~~~~~~~~~~~~~~~
      ! R_function2_param1
      ! ~~~~~~~~~~~~~~~~~~
      ! R_function2_param2
      ! ~~~~~~~~~~~~~~~~~~

      ! ::

      !     R_function2 = R_function2_weight*min(R_function2_param1,max(R_function2_param2,r/Rstar))

      ! where Rstar = radius of outer edge of model.

      ! ::

    R_function2_weight = 0
    R_function2_param1 = 0.4d0
    R_function2_param2 = 0


      ! R_function3_weight
      ! ~~~~~~~~~~~~~~~~~~

      ! radius gradient

      ! ::

      !     R_function3 = R_function3_weight*(r/Rstar)

      ! ::

    R_function3_weight = 0


      ! M_function_weight
      ! ~~~~~~~~~~~~~~~~~
      ! M_function_param
      ! ~~~~~~~~~~~~~~~~

      ! log mass gradient

      ! ::

      !     M_function = M_function_weight*log10(1 + (m/Msun)/M_function_param)

      ! ::

    M_function_weight = 0
    M_function_param = 1d-6


      ! gradT_function_weight
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! gradT gradient, ``gradT_function = gradT_function_weight*gradT``

      ! ::

    gradT_function_weight = 0


      ! log_tau_function_weight
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! log_tau gradient (optical depth)

      ! ::

      !     log_tau_function = log_tau_function_weight*log10(tau)

      ! ::

    log_tau_function_weight = 0


      ! log_kap_function_weight
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! log_kap gradient (optical depth)

      ! ::

      !     log_kap_function = log_kap_function_weight*log10(kap)

      ! ::

    log_kap_function_weight = 0


      ! omega_function_weight
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! omega gradient (rotation omega in rad/sec)

      ! ::

      !     omega_function = omega_function_weight*log10(omega)

      ! ::

    omega_function_weight = 0


      ! gam_function_weight
      ! ~~~~~~~~~~~~~~~~~~~
      ! gam_function_param1
      ! ~~~~~~~~~~~~~~~~~~~
      ! gam_function_param2
      ! ~~~~~~~~~~~~~~~~~~~

      ! For extra resolution around liquid/solid transition.

      ! ::

      !     gam = plasma interaction parameter
      !     gam_function = gam_function_weight*tanh((gam - gam_function_param1)/gam_function_param2)

      ! ::

    gam_function_weight = 0
    gam_function_param1 = 170
    gam_function_param2 = 20


      ! xa_function_species
      ! ~~~~~~~~~~~~~~~~~~~
      ! xa_function_weight
      ! ~~~~~~~~~~~~~~~~~~

      ! Mass fraction gradients.

      ! ::

      !     xa_function = xa_function_weight*log10(xa + xa_function_param),

      ! Up to ``num_xa_function`` of these - see ``star_def`` for value of ``num_xa_function``.
      ! 0 length string means skip, otherwise name of nuclide as defined in ``chem_def``.
      ! weight <= 0 means skip.

      ! ::

    xa_function_species(:) = ''
    xa_function_weight(:) = 0

      ! ::

    xa_function_species(1) = 'he4'
    xa_function_weight(1) = 30
    xa_function_param(1) = 1d-2


      ! xa_mesh_delta_coeff
      ! ~~~~~~~~~~~~~~~~~~~

      ! Useful if you want to increase ``mesh_delta_coeff`` during advanced burning.
      ! If ``xa_function_species(j)`` has the largest atomic number in current set of species,
      ! then multiply ``mesh_delta_coeff`` by ``xa_mesh_delta_coeff(j)``.

      ! ::

    xa_mesh_delta_coeff(:) = 1


      ! mesh_delta_coeff_factor_smooth_iters
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Some smoothing is useful when using local changes to mesh_delta_coeff.

      ! ::

    mesh_delta_coeff_factor_smooth_iters = 3

      ! "Indirect" mesh controls work by increasing sensitivity in selected regions.
      ! They work in the same way as ``mesh_delta_coeff`` -- values less than 1.0 mean
      ! smaller allowed jumps in mesh functions and hence smaller grid points and
      ! higher resolution.  But whereas ``mesh_delta_coeff`` applies uniformly to all
      ! cells, the "extra" coefficients can vary in value from one cell to the next.

      ! Note that you can set your own local changes by means of the hook other_mesh_delta_coeff_factor.


      ! mesh_logX_species
      ! ~~~~~~~~~~~~~~~~~
      ! mesh_logX_min_for_extra
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Increase resolution at points with large abs(dlogX/dlogP); logX = log10(X mass fraction).

      ! ::

    mesh_logX_species(1) = ''
    mesh_logX_min_for_extra(1) = -6


      ! mesh_dlogX_dlogP_extra(1)
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! mesh_dlogX_dlogP_full_on(1)
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! mesh_dlogX_dlogP_full_off(1)
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Only increase resolution if ``logX >= mesh_logX_min_for_extra``.
      ! Make ``mesh_dlogX_dlogP_extra < 1`` for smaller allowed change in logP and hence higher resolution.
      ! Full effect if ``abs(dlogX/dlogP) >= mesh_dlogX_dlogP_full_on``.
      ! No effect if ``abs(dlogX/dlogP)) <= mesh_dlogX_dlogP_full_off``.
      ! Up to ``num_mesh_logX`` of these (see ``star_def`` for value of ``num_mesh_logX``).

      ! ::

    mesh_dlogX_dlogP_extra(1) = 1
    mesh_dlogX_dlogP_full_on(1) = 2
    mesh_dlogX_dlogP_full_off(1) = 1

      ! Multiply ``mesh_delta_coeff`` near convection zone boundary (czb) by the following factors.
      ! Value < 1 gives increased resolution.


      ! Increase resolution at points with large ``abs(dlog_eps/dlogP)`` for nuclear power eps (ergs/g/sec).
      ! At any particular location, only use eps nuc category with max local value
      ! e.g., only use ``mesh_dlog_pp_dlogP_extra`` at points where pp is the max burn source.


      ! mesh_dlog_eps_min_for_extra
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Only increase resolution if ``log_eps >= mesh_dlog_eps_min_for_extra``.

      ! ::

    mesh_dlog_eps_min_for_extra = -2


      ! mesh_dlog_eps_dlogP_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Full effect if ``abs(dlog_eps/dlogP) >= mesh_dlog_eps_dlogP_full_on``.

      ! ::

    mesh_dlog_eps_dlogP_full_on = 4


      ! mesh_dlog_eps_dlogP_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! No effect if ``abs(dlog_eps/dlogP)) <= mesh_dlog_eps_dlogP_full_off``.

      ! ::

    mesh_dlog_eps_dlogP_full_off = 1

      ! Multiply the allowed change between adjacent cells by the following factors;
      ! (small factor => smaller allowed change => more cells).

      ! pp and cno burning

      ! ::

    mesh_dlog_pp_dlogP_extra = 0.25d0
    mesh_dlog_cno_dlogP_extra = 0.25d0

      ! triple alpha, c, n, and o burning

      ! ::

    mesh_dlog_3alf_dlogP_extra = 0.25d0
    mesh_dlog_burn_c_dlogP_extra = 0.25d0
    mesh_dlog_burn_n_dlogP_extra = 0.25d0
    mesh_dlog_burn_o_dlogP_extra = 0.25d0

      ! ne, na, and mg burning

      ! ::

    mesh_dlog_burn_ne_dlogP_extra = 0.25d0
    mesh_dlog_burn_na_dlogP_extra = 0.25d0
    mesh_dlog_burn_mg_dlogP_extra = 0.25d0

      ! c12+c12. c12+o16, and o16+o16 burning

      ! ::

    mesh_dlog_cc_dlogP_extra = 0.25d0
    mesh_dlog_co_dlogP_extra = 0.25d0
    mesh_dlog_oo_dlogP_extra = 0.25d0

      ! si to iron along alpha chain burning

      ! ::

    mesh_dlog_burn_si_dlogP_extra = 0.25d0
    mesh_dlog_burn_s_dlogP_extra = 0.25d0
    mesh_dlog_burn_ar_dlogP_extra = 0.25d0
    mesh_dlog_burn_ca_dlogP_extra = 0.25d0
    mesh_dlog_burn_ti_dlogP_extra = 0.25d0
    mesh_dlog_burn_cr_dlogP_extra = 0.25d0
    mesh_dlog_burn_fe_dlogP_extra = 0.25d0

      ! photodisintegration burning

      ! ::

    mesh_dlog_pnhe4_dlogP_extra = 0.25d0
    mesh_dlog_other_dlogP_extra = 0.25d0
    mesh_dlog_photo_dlogP_extra = 1

      ! convective_bdy_weight
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! convective_bdy_dq_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! convective_bdy_min_dt_yrs
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Mesh function to enhance resolution near convective boundaries

      ! ::

      convective_bdy_weight = 0
      convective_bdy_dq_limit = 3d-5
      convective_bdy_min_dt_yrs = 1d-3

      ! max_rel_delta_IE_for_mesh_total_energy_balance
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! remeshing can adjust internal energy of cell by this fraction
      ! in order to maintain total internal + potential + kinetic energy.

      ! ::

    max_rel_delta_IE_for_mesh_total_energy_balance = 0.05d0


      ! trace_mesh_adjust_error_in_conservation
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, report relative errors for total PE, KE, and IE.
      ! (potential, kinetic, internal).

      ! ::

    trace_mesh_adjust_error_in_conservation = .false.


      ! okay_to_remesh
      ! ~~~~~~~~~~~~~~

      ! If false, then no remeshing.

      ! ::

    okay_to_remesh = .true.


      ! restore_mesh_on_retry
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! If true, then after a retry the remeshing is undone for the step,
      ! and the following try is performed with the same mesh used in the
      ! previous step. This can help with the retry by reducing the changes.

      ! ::

    restore_mesh_on_retry = .false.


      ! num_steps_to_hold_mesh_after_retry
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! When restore_mesh_on_retry=true, then after a retry remeshing is not done
      ! for this number of steps.

      ! ::

    num_steps_to_hold_mesh_after_retry = 0


      ! remesh_dt_limit
      ! ~~~~~~~~~~~~~~~

      ! No remesh if ``dt < remesh_dt_limit``, in seconds.

      ! ::

    remesh_dt_limit = -1


      ! TDC_hydro_nz
      ! ~~~~~~~~~~~~
      ! TDC_hydro_nz_outer
      ! ~~~~~~~~~~~~~~~~~~
      ! TDC_hydro_T_anchor
      ! ~~~~~~~~~~~~~~~~~~
      ! TDC_hydro_dq_1_factor
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! TDC_hydro_use_mass_interp_face_values
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! remesh_for_TDC_pulsations_log_core_zoning
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If calling the public ``remesh_for_TDC_pulsations`` function, the model will be rezoned below ``TDC_hydro_T_anchor`` with logarithmic
      ! spacing in mass. If .false., remeshing scheme will do a bisection root find such
      ! that each zone increases in mass inward following a power law, similar to RSP's static model builder.

      ! The total number of zones is set by ``TDC_hydro_nz``, with constant spacing in mass between the surface and
      ! ``TDC_hydro_T_anchor``, and increasing spacing in mass between the anchor and the inner boundary condition.
      ! The number of zones in between the anchor and the surface is set by ``TDC_hydro_nz_outer``, and the number of
      ! zones in the interior is set by ``TDC_hydro_nz`` - ``TDC_hydro_nz_outer``.
      ! The ``TDC_hydro_dq_1_factor`` sets the dq of the surface cell to this multiple of the cell beneath it, k = 2.

      ! ``TDC_hydro_use_mass_interp_face_values`` determines whether quantities are averaged to faces using simple average or
      ! mass weighted averaging.

      ! This remeshing scheme works well for most Cepheid envelopes, but it is not designed for AGB stars with deep convective envelopes.

      ! ::

    remesh_for_TDC_pulsations_log_core_zoning = .false.
    TDC_hydro_use_mass_interp_face_values = .false.

    TDC_hydro_nz = 150
    TDC_hydro_nz_outer = 40
    TDC_hydro_T_anchor = 11d3
    TDC_hydro_dq_1_factor = 2d0


      ! use_split_merge_amr
      ! ~~~~~~~~~~~~~~~~~~~

      ! ::

    use_split_merge_amr = .false.


      ! split_merge_amr_logtau_zoning
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! split_merge_amr_log_zoning
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! split_merge_amr_hybrid_zoning
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! split_merge_amr_flipped_hybrid_zoning
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if split_merge_amr_logtau_zoning, target is even grid spacing in logtau
      ! else if split_merge_amr_log_zoning, target is even grid spacing in logr
      ! else if split_merge_amr_hybrid_zoning, target is even r spacing for core, even logr outside
      ! else if split_merge_amr_flipped_hybrid_zoning, target is even logr spacing for core, even r outside
      ! else target is even grid spacing in r

      ! ::

    split_merge_amr_logtau_zoning = .false.
    split_merge_amr_log_zoning = .true.
    split_merge_amr_hybrid_zoning = .false.
    split_merge_amr_flipped_hybrid_zoning = .false.


      ! split_merge_amr_nz_baseline
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! split_merge_amr_nz_r_core
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! split_merge_amr_nz_r_core_fraction
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! split_merge_amr_mesh_delta_coeff
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    split_merge_amr_nz_baseline = 1000
    split_merge_amr_nz_r_core = 0d0 ! ignore if <= 0
    split_merge_amr_nz_r_core_fraction = 0d0 ! ignore if <= 0; else r_core = r_center + fraction*(r(1) - r_center)
    split_merge_amr_mesh_delta_coeff = 1d0 ! like mesh_delta_coeff, but for amr


      ! split_merge_amr_MaxLong
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! split_merge_amr_MaxShort
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! split cell if ratio of actual/desired size is > split_merge_amr_MaxLong; ignore if <= 0
      ! merge cell if ratio of desired/actual size is < split_merge_amr_MaxShort; ignore if <= 0
      ! be careful to avoid inconsistent limits such as when a required split triggers a required merge.
      ! to be safe, make sure product of limits > 2.

      ! ::

    split_merge_amr_MaxLong = 1.5d0
    split_merge_amr_MaxShort = 1.5d0


      ! merge_amr_max_abs_du_div_cs
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    merge_amr_max_abs_du_div_cs = 0.1d0


      ! merge_amr_du_div_cs_limit_only_for_compression
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, then merge_amr_max_abs_du_div_cs limit will only be considered
      ! for cells that would undergo compression

      ! ::

    merge_amr_du_div_cs_limit_only_for_compression = .false.


      ! merge_amr_inhibit_at_jumps
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    merge_amr_inhibit_at_jumps = .false.


      ! merge_amr_ignore_surface_cells
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! merge_amr_k_for_ignore_surface_cells
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Merging surface cells can cause problems. If merge_amr_ignore_surface_cells is true,
      ! then the outermost merge_amr_k_for_ignore_surface_cells cells are ignored for merge.

      ! ::

    merge_amr_ignore_surface_cells = .true.
    merge_amr_k_for_ignore_surface_cells = 2


      ! merge_amr_ignore_core_cells
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! merge_amr_logT_for_ignore_core_cells
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! split_amr_ignore_core_cells
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! split_amr_logT_for_ignore_core_cells
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! For pulsation calculations, splitting and merging core cells can cause problems.
      ! If merge_amr_ignore_core_cells or split_amr_ignore_surface_cells is true,
      ! then the innermost cells above merge_amr_logT_for_ignore_core_cells or
      ! split_amr_logT_for_ignore_core_cells  cells are ignored for split/merge.

      ! ::

    merge_amr_ignore_core_cells = .false.
    merge_amr_logT_for_ignore_core_cells = 1d99
    split_amr_ignore_core_cells = .false.
    split_amr_logT_for_ignore_core_cells = 1d99


      ! split_merge_amr_avoid_repeated_remesh
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, then after a cell has been merged or split, the resulting cell will not be considered
      ! in further remeshing for this step.

      ! ::

    split_merge_amr_avoid_repeated_remesh = .false.


      ! split_merge_amr_dq_min
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! split_merge_amr_dq_max
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    split_merge_amr_dq_min = 1d-14
    split_merge_amr_dq_max = 1d0


      ! split_merge_amr_r_core_cm
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    split_merge_amr_r_core_cm = 1d8


      ! split_merge_amr_max_iters
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    split_merge_amr_max_iters = 100


      ! split_merge_amr_okay_to_split_1
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! split_merge_amr_okay_to_split_nz
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    split_merge_amr_okay_to_split_1 = .true.
    split_merge_amr_okay_to_split_nz = .true.


      ! equal_split_density_amr
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    equal_split_density_amr = .false.


      ! trace_split_merge_amr
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! ::

    trace_split_merge_amr = .false.

! nuclear reaction controls
! =========================


      ! default_net_name
      ! ~~~~~~~~~~~~~~~~

      ! Name of base reaction network (including 8 isotopes to capture energy release)
      ! Will auto-extend to ``co_burn.net`` (adding si28) at He depletion, and to
      ! ``approx21.net`` (adding 21 isotopes and a "fake" electron capture reaction for
      ! deleptonization, see ``fe56ec_fake_factor`` below). Each net corresponds to a
      ! file in ``$MESA_DIR/data/net_data/nets``. Look in that directory to see
      ! your network options, or learn how to create your own net.
      ! See also ``change_net`` and related options in ``star_job.defaults``.

      ! ::

    default_net_name = 'basic.net'


      ! screening_mode
      ! ~~~~~~~~~~~~~~

      ! + empty string means no screening
      ! + ``' extended'`` :
      !   extends the Graboske (1973) method using results from Alastuey and Jancovici (1978),
      !   along with plasma parameters from Itoh et al (1979) for strong screening.
      ! + ``'salpeter'`` :
      !   weak screening only.  following Salpeter (1954),
      !   with equations (4-215) and (4-221) of Clayton (1968).
      ! + ``'chugunov'`` :
      !   based on code from Sam Jones
      !   Implements screening from Chugunov et al (2007) for weak and strong screening
      !   MESA versions <=11435 used extended as the default value

      ! ::

    screening_mode = 'chugunov'


      ! net_logTcut_lo
      ! ~~~~~~~~~~~~~~

      ! strong rates are zero ``logT < logTcut_lo``
      ! use default from net if this is <= 0

      ! ::

    net_logTcut_lo = -1


      ! net_logTcut_lim
      ! ~~~~~~~~~~~~~~~

      ! strong rates cutoff smoothly for ``logT < logTcut_lim``
      ! use default from net if this is <= 0

      ! ::

    net_logTcut_lim = -1


      ! max_abar_for_burning
      ! ~~~~~~~~~~~~~~~~~~~~

      ! if abar > this, suppress all burning
      ! e.g., if you want an "inert" core heavy elements, set this to 55
      ! or, if you want to turn off the net, set this to -1

      ! ::

    max_abar_for_burning = 199


      ! dxdt_nuc_factor
      ! ~~~~~~~~~~~~~~~

      ! Control for abundance changes by burning.
      ! Changes ``dxdt_nuc`` (rate of change of abundances)
      ! without changing the rates or ``eps_nuc`` (rate of energy generation).

      ! ::

    dxdt_nuc_factor = 1


      ! weak_rate_factor
      ! ~~~~~~~~~~~~~~~~

      ! all weak rates are multiplied by this factor

      ! ::

    weak_rate_factor = 1


      ! reaction_neuQs_factor
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! all neutrino Q factors are multiplied by this factor

      ! ::

    reaction_neuQs_factor = 1


      ! nonlocal_NiCo_kap_gamma
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    nonlocal_NiCo_kap_gamma = 0


      ! nonlocal_NiCo_decay_heat
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! if true, do non-local deposition of gamma-ray energy from Ni56 and Co56 decays.
      ! only for approx nets including co56.
      ! intended for use with stripped envelope supernovae.

      ! ::

    nonlocal_NiCo_decay_heat = .false.


      ! dtau_gamma_NiCo_decay_heat
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    dtau_gamma_NiCo_decay_heat = 1d0


      ! max_logT_for_net
      ! ~~~~~~~~~~~~~~~~

      ! ::

    max_logT_for_net = 10.2d0

! element diffusion
! =================

      ! gravitational settling and chemical diffusion.


      ! show_diffusion_info
      ! ~~~~~~~~~~~~~~~~~~~

      ! terminal output for diffusion

      ! ::

    show_diffusion_info = .false.


      ! show_diffusion_substep_info
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! terminal output for diffusion

      ! ::

    show_diffusion_substep_info = .false.


      ! show_diffusion_timing
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! show time for each call on diffusion

      ! ::

    show_diffusion_timing = .false.


      ! do_element_diffusion
      ! ~~~~~~~~~~~~~~~~~~~~

      ! determines whether or not we do element diffusion

      ! ::

    do_element_diffusion = .false.


      ! diffusion_dt_limit
      ! ~~~~~~~~~~~~~~~~~~

      ! no element diffusion if dt < this limit (in seconds)

      ! ::

    diffusion_dt_limit = 3.15d7

      ! diffusion_use_paquette
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! if true, use atomic diffusion coefficients according to Paquette et al. (1986).
      ! if false, use Stanton & Murillo PhRvE, 93, 043203 (2016) for diffusion coefficients.
      ! (Paquette coefficients still used for electron-ion because Stanton & Murillo
      ! did not do calculations for attractive potentials.)

      ! ::

    diffusion_use_paquette = .false.


      ! diffusion_use_caplan
      ! ~~~~~~~~~~~~~~~~~~~~

      ! if true, use atomic diffusion coefficients according to
      ! Caplan, Bauer, & Freeman MNRAS, 513, L52 (2022) at strong coupling (Gamma > 10),
      ! relevant for white dwarf interiors.

      ! ::

    diffusion_use_caplan = .true.


      ! diffusion_use_iben_macdonald
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if true, use diffusion coefficients similar to Iben & MacDonald (1985).
      ! if false, use Stanton & Murillo (2016) for diffusion coefficients.
      ! this was previously called ``diffusion_use_pure_coulomb``.

      ! ::

    diffusion_use_iben_macdonald = .false.


      ! diffusion_use_cgs_solver
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! if false, solve the system of equations described by Thoul et al. (1994)
      ! if true, solve the unmodified Burgers equations in cgs units

      ! ::

    diffusion_use_cgs_solver = .true.


      ! cgs_thermal_diffusion_eta_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! cgs_thermal_diffusion_eta_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! When ``diffusion_use_cgs_solver = .true.``
      ! for ``eta < cgs_thermal_diffusion_eta_full_on``,
      ! includes the heat flow vector terms in the Burgers equations.
      ! Then smoothly turns off use of these terms so that they are not included
      ! for ``eta > cgs_thermal_diffusion_eta_full_off``, since these terms are
      ! problematic when distribution function become non-Maxwellian.

      ! ::

    cgs_thermal_diffusion_eta_full_on = 0d0
    cgs_thermal_diffusion_eta_full_off = 2d0


      ! do_WD_sedimentation_heating
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_xa_for_WD_sedimentation_heating
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if true, include heating associated with sedimentation when element diffusion is on.
      ! Only elements with mass fraction > min_xa_for_WD_sedimentation_heating
      ! will be included in this calculation.
      ! For best results, set diffusion_use_full_net = .true.
      ! This will affect white dwarf cooling times.
      ! See also ``eps_WD_sedimentation_factor``

      ! ::

    do_WD_sedimentation_heating = .false.
    min_xa_for_WD_sedimentation_heating = 1d-5


      ! do_diffusion_heating
      ! ~~~~~~~~~~~~~~~~~~~~

      ! if true, calculate heating term associated with changes in
      ! internal energy due to any abundance changes from element
      ! diffusion, and include this term in the energy equation.
      ! To avoid double-counting, this control can only be used if
      ! do_WD_sedimentation_heating = .false.

      ! ::

    do_diffusion_heating = .true.


      ! diffusion_min_dq_at_surface
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! treat at least this much at surface as a single cell for purposes of diffusion

      ! ::

    diffusion_min_dq_at_surface = 1d-9


      ! diffusion_min_T_at_surface
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! treat cells cells at surface with T < this as a single cell for purposes of diffusion
      ! default should be large enough to ensure hydrogen ionization

      ! ::

    diffusion_min_T_at_surface = 1d4


      ! diffusion_min_dq_ratio_at_surface
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! combine cells at surface until have total mass >= this factor times the next cell below them
      ! this helps with surface boundary condition for diffusion by putting large cell at surface

      ! ::

    diffusion_min_dq_ratio_at_surface = 10


      ! diffusion_dt_div_timescale
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! dt is at most this fraction of timescale.
      ! Each stellar evolution step can be divided into many substeps for diffusion.
      ! The substep timescale is set by rates of flow in and out for each species in each cell.
      ! The substep size, dt, is initially set to ``timescale*diffusion_dt_div_timescale``.

      ! ::

    diffusion_dt_div_timescale = 1


      ! diffusion_min_num_substeps
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Max substep dt is total time divided by this.

      ! ::

    diffusion_min_num_substeps = 1


      ! diffusion_max_iters_per_substep
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If the substep requires too many iterations, the substep time is decreased for a retry.

      ! ::

    diffusion_max_iters_per_substep = 10


      ! diffusion_max_retries_per_substep
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If the substep requires too many retries, diffusion fails and forces a retry for the star.

      ! ::

    diffusion_max_retries_per_substep = 10


      ! diffusion_tol_correction_max
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! diffusion_tol_correction_norm
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Tolerances for solver iterations.
      ! Corrections smaller will be treated as converged.
      ! Corrections larger will cause another solver iteration.

      ! ::

    diffusion_tol_correction_max = 1d-1
    diffusion_tol_correction_norm = 1d-3


      ! diffusion_min_X_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! tolerance for negative mass fraction errors
      ! errors larger will cause retry; errors smaller will be corrected.
      ! Tightening this control may help with "failed in fixup"
      ! errors when diffusion_use_isolve = .true.

      ! ::

    diffusion_min_X_hard_limit = -1d-3


      ! diffusion_X_total_atol
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! diffusion_X_total_rtol
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! tolerances for errors in total species conservation
      ! errors larger will cause retry; errors smaller will be corrected.

      ! ::

    diffusion_X_total_atol = 1d-9
    diffusion_X_total_rtol = 1d-6


      ! diffusion_upwind_abs_v_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! switch to upwind for i at face k if abs(v(i,k)) > this limit
      ! mainly for use with radiative levitation where get very much higher velocities

      ! ::

    diffusion_upwind_abs_v_limit = 1d99


      ! diffusion_v_max
      ! ~~~~~~~~~~~~~~~

      ! Max velocity (cm/sec).
      ! We can get extremely large velocities in the extreme outer envelope
      ! that cause problems numerically without really effecting the results,
      ! so we allow a max for the velocities that should help the numerics
      ! without changing the results.
      ! Note: change ``diffusion_v_max`` to at least 1d-2 when using radiative levitation.

      ! ::

    diffusion_v_max = 1d-3


      ! D_mix_ignore_diffusion
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Diffusion is turned off in core and surface convection zones,
      ! since it is overwhelmed by other mixing there.
      ! D_mix_ignore_diffusion roughly defines the mixing coefficient
      ! below which diffusion is included again. The code finds the
      ! location where D_mix falls to this value, backs up some,
      ! and turns on diffusion from there onward.

      ! ::

    D_mix_ignore_diffusion = 1d5


      ! diffusion_gamma_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! diffusion_gamma_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! ``gamma_full_on <= gamma_full_off``
      ! Shut off diffusion for large gamma (i.e. for ``gamma >= gamma_full_off``).
      ! Gradually decrease diffusion as gamma increases from ``full_on`` to ``full_off``.
      ! Allow normal diffusion for ``gamma <= gamma_full_on``.
      ! Default is diffusion off when get well into liquid regime.

      ! ::

    diffusion_gamma_full_off = 1d99
    diffusion_gamma_full_on = 1d99


      ! diffusion_T_full_on
      ! ~~~~~~~~~~~~~~~~~~~
      ! diffusion_T_full_off
      ! ~~~~~~~~~~~~~~~~~~~~

      ! ``T_full_on >= T_full_off``
      ! Shut off diffusion for small T (i.e., for ``T <= T_full_off``)
      ! Gradually decrease diffusion as T decreases from ``T_full_on`` to ``T_full_off``.
      ! Allow normal diffusion for ``T >= T_full_on``.

      ! ::

    diffusion_T_full_on = 1d3
    diffusion_T_full_off = 1d3


      ! diffusion_calculates_ionization
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If ``diffusion_calculates_ionization`` is false, MESA uses
      ! typical charges for a set of representative species as
      ! defined in ``diffusion_class_typical_charge`` and
      ! ``diffusion_class_representative`` for all points rather than
      ! calculating the ionization from the local conditions.

      ! ::

    diffusion_calculates_ionization = .true.


      ! diffusion_nsmooth_typical_charge
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! smoothing over charge

      ! ::

    diffusion_nsmooth_typical_charge = 10


      ! diffusion_SIG_factor
      ! ~~~~~~~~~~~~~~~~~~~~
      ! diffusion_GT_factor
      ! ~~~~~~~~~~~~~~~~~~~

      ! factors for playing with SIG and GT terms for concentration diffusion and advection

      ! ::

    diffusion_SIG_factor = 1d0
    diffusion_GT_factor = 1d0


      ! diffusion_AD_dm_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! diffusion_AD_dm_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! diffusion_AD_boost_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! artificial concentration diffusion near surface (mainly for radiative levitation)
      ! Msun units for ``full_on`` and ``full_off``
      ! boost only used if > 0

      ! ::

    diffusion_AD_dm_full_on = -1
    diffusion_AD_dm_full_off = -1
    diffusion_AD_boost_factor = 0


      ! diffusion_Vlimit_dm_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! diffusion_Vlimit_dm_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! in Msun units
      ! artificial velocity limitation near surface (mainly for radiative levitation)

      ! ::

    diffusion_Vlimit_dm_full_on = -1
    diffusion_Vlimit_dm_full_off = -1


      ! diffusion_Vlimit
      ! ~~~~~~~~~~~~~~~~

      ! In units of local cell crossing velocity (only used if > 0).
      ! When full on, limit ``abs(v) <= Vlimit*dr/dt``, cell size dr, substep time dt.

      ! ::

    diffusion_Vlimit = 0


      ! D_mix_zero_region_bottom_q
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! D_mix_zero_region_top_q
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! dq_D_mix_zero_at_H_He_crossover
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! dq_D_mix_zero_at_H_C_crossover
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

   D_mix_zero_region_bottom_q = 1d99
   D_mix_zero_region_top_q = -1d99
   dq_D_mix_zero_at_H_He_crossover = -1d0
   dq_D_mix_zero_at_H_C_crossover = -1d0


      ! diffusion_min_T_for_radaccel
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! diffusion_max_T_for_radaccel
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If T between these limits, then include radiative levitation at that location.
      ! Calculation of radiative levitation is costly, so only use it where necessary.
      ! Note: change ``diffusion_v_max`` to at least 1d-2 when using radiative levitation.

      ! Note that radiative levitation requires OP calculations
      ! of g_rad for each class, and only 17 elements are supported
      ! (H, He, C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Cr, Mn, Fe, Ni).
      ! If you want to include radiative levitation, your options are:
      ! + Define diffusion classes such that all class representatives are among the 17 elements listed above.
      ! + Use a net with only elements from the 17 above, and set diffusion_use_full_net = .true.

      ! ::

    diffusion_min_T_for_radaccel = 0
    diffusion_max_T_for_radaccel = 0


      ! diffusion_min_Z_for_radaccel
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! diffusion_max_Z_for_radaccel
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If Z between these limits, then include radiative levitation for that element.
      ! Calculation of radiative levitation is costly, so only use it where necessary.
      ! e.g., limit to Fe and Ni by ``min_Z = 26`` and ``max_Z = 28``

      ! ::

    diffusion_min_Z_for_radaccel = 0
    diffusion_max_Z_for_radaccel = 1000


      ! diffusion_screening_for_radaccel
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Include screening for radiative levitation.

      ! ::

    diffusion_screening_for_radaccel = .true.


      ! diffusion_use_full_net
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! If true, don't lump elements into classes for diffusion.
      ! Instead, each isotope in the network is treated as its own separate class.
      ! This can cause significant slowdowns for large nets, so it is off by default.
      ! This works for nets with up to 100 isotopes; larger nets require lumping into
      ! classes.

      ! ::

    diffusion_use_full_net = .false.


      ! diffusion_num_classes
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Number of representative classes of species for diffusion calculations.
      ! (maximum of 100)

      ! ::

    diffusion_num_classes = 5


      ! diffusion_class_representative(:)
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! isotope names for diffusion representatives

      ! ::

    diffusion_class_representative(1) = 'h1'
    diffusion_class_representative(2) = 'he3'
    diffusion_class_representative(3) = 'he4'
    diffusion_class_representative(4) = 'o16'
    diffusion_class_representative(5) = 'fe56'


      ! diffusion_class_A_max(:)
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! atomic number A. in ascending order.  species goes into 1st class with ``A_max`` >= species A

      ! ::

    diffusion_class_A_max(1) = 2
    diffusion_class_A_max(2) = 3
    diffusion_class_A_max(3) = 4
    diffusion_class_A_max(4) = 16
    diffusion_class_A_max(5) = 10000


      ! diffusion_class_typical_charge(:)
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Typical charges for use if ``diffusion_calculates_ionization`` is false
      ! Use charge 21 for Fe in the sun, from
      ! Thoul, Bahcall, and Loeb (1994), ApJ, 421, 828.

      ! ::

    diffusion_class_typical_charge(1) = 1
    diffusion_class_typical_charge(2) = 2
    diffusion_class_typical_charge(3) = 2
    diffusion_class_typical_charge(4) = 8
    diffusion_class_typical_charge(5) = 21


      ! diffusion_class_factor(:)
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Arbitrarily enhance or inhibit diffusion effects by class.

      ! ::

    diffusion_class_factor(:) = 1d0


   ! parameters for ionization solver
   ! ________________________________


      ! diffusion_use_isolve
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Activate iterative solver.

      ! ::

    diffusion_use_isolve = .false.


      ! diffusion_rtol_for_isolve
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! diffusion_atol_for_isolve
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Relative and absolute error parameters for iterative solver.

      ! ::

    diffusion_rtol_for_isolve = 1d-4
    diffusion_atol_for_isolve = 1d-5


      ! diffusion_maxsteps_for_isolve
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Maximum number of steps to take in iterative solver.

      ! ::

    diffusion_maxsteps_for_isolve = 1000


      ! diffusion_isolve_solver
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Which ode solver to use for iterative.

      ! Options include:

      ! + ``'ros2_solver'``
      ! + ``'rose2_solver'``
      ! + ``'ros3p_solver'``
      ! + ``'ros3pl_solver'``
      ! + ``'rodas3_solver'``
      ! + ``'rodas4_solver'``
      ! + ``'rodasp_solver'``

      ! ::

    diffusion_isolve_solver = 'ros2_solver'


      ! diffusion_dump_call_number
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! debugging info of diffusion at call number

      ! ::

    diffusion_dump_call_number = -1


! WD phase separation
! ===================

      ! do_phase_separation
      ! ~~~~~~~~~~~~~~~~~~~

      ! Phase separation upon crystallization in WD cores
      ! using the implementation of `Bauer (2023) <https://ui.adsabs.harvard.edu/abs/2023ApJ...950..115B>`_.

      ! ::

    do_phase_separation = .false.

      ! phase_separation_option
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Choice of appropriate option for the WD core mixture:

      ! + ``'CO'`` : carbon-oxygen phase separation using the two-component
      !   phase diagram of `Blouin & Daligault (2021a) <https://ui.adsabs.harvard.edu/abs/2021PhRvE.103d3204B>`_.
      ! + ``'ONe'`` : oxygen-neon phase separation using the two-component
      !   phase diagram of `Blouin & Daligault (2021b) <https://ui.adsabs.harvard.edu/abs/2021ApJ...919...87B>`_.

      ! ::

    phase_separation_option = 'CO'

      ! do_phase_separation_heating
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if true, calculate heating term associated with changes in
      ! internal energy due to any abundance changes from phase
      ! separation, and include this term in the energy equation.

      ! ::

    do_phase_separation_heating = .true.

      ! phase_separation_mixing_use_brunt
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if true, the phase separation mixing recalculates relevant
      ! EOS quantities and evaluates the Ledoux criterion,
      ! including the brunt B term that depends on the composition
      ! gradient. This can be somewhat expensive, so this option can
      ! be set to false to instead just mix outward until there is
      ! no more negative mu gradient. These will produce similar
      ! final chemical profiles, but setting this option to true
      ! is the only way to properly evaluate the physical criterion.

      ! ::

    phase_separation_mixing_use_brunt = .true.


! eos controls
! ============

      ! fix_d_eos_dxa_partials
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! The star solver uses the partial derivatives of lnPgas and lnE
      ! with respect to composition.  When the EOS fails to provide
      ! these, replace them with a finite-difference approximation.

      ! ::

    fix_d_eos_dxa_partials = .true.

! opacity controls
! ================

      ! more opacity controls can be found in ``star_job.defaults``


      ! use_simple_es_for_kap
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! for experiments with simple electron scattering
      ! if true, ``opacity = 0.2*(1 + X)``

      ! ::

    use_simple_es_for_kap = .false.


      ! use_starting_composition_for_kap
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! for experiments with partials of opacity with respect to composition
      ! if true, calls on kap during solver iterations use the starting composition

      ! ::

    use_starting_composition_for_kap = .false.


      ! opacity_min
      ! ~~~~~~~~~~~

      ! limit minimum opacities to this value (ignore this if value is < 0)

      ! ::

    opacity_min = -1

      ! opacity_max
      ! ~~~~~~~~~~~

      ! limit opacities to this value (ignore this if value is < 0)

      ! ::

    opacity_max = -1


      ! opacity_factor
      ! ~~~~~~~~~~~~~~

      ! opacities are multiplied by this value

      ! ::

    opacity_factor = 1


      ! min_logT_for_opacity_factor_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_logT_for_opacity_factor_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_logT_for_opacity_factor_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_logT_for_opacity_factor_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! temperature controls for where the ``opacity_factor`` is applied
      ! if, for example, you only want the opacity factor to apply in the iron bump region
      ! you can give a logT range such as

      ! ::

      !     min_logT_for_opacity_factor_off = 5.2
      !     min_logT_for_opacity_factor_on = 5.3
      !     max_logT_for_opacity_factor_on = 5.7
      !     max_logT_for_opacity_factor_off = 5.8

      ! ignore these if < 0.

      ! ::

    min_logT_for_opacity_factor_off = -1
    min_logT_for_opacity_factor_on = -1
    max_logT_for_opacity_factor_on = -1
    max_logT_for_opacity_factor_off = -1

      ! if you need cell-by-cell control of opacity factor,
      ! set the vector "``extra_opacity_factor``" using the routine "``other_opacity_factor``"


   ! OP mono opacities
   ! _________________

      ! The ``OP_mono`` opacities use data and code from the OP website
      ! as modified by Haili Hu.  Since the tar.xz file is large (462 MB),
      ! it is not included in the standard mesa download.

      ! You can get ``OP4STARS_1.3.tar.xz`` from https://zenodo.org/records/4390522

      ! Put it any place you want on your disk.

      ! ::

      !     tar -xf OP4STARS_1.3.tar.xz

      ! Set the inlist controls for the "mono" directory with the data files.
      ! For example, in my case it looks like the following, but you can put
      ! the directory anywhere you like -- it doesn't need to be in the mesa/data
      ! directory. And the cache file doesn't need to be in the mono directory.

      ! ::

      !     op_mono_data_path = '/Users/bpaxton/OP4STARS_1.3/mono'
      !     op_mono_data_cache_filename = '/Users/bpaxton/OP4STARS_1.3/mono/op_mono_cache.bin'

      ! If you use these opacities, you should cite `Seaton (2005)`_.

      ! .. _Seaton (2005): https://ui.adsabs.harvard.edu/abs/2005MNRAS.362L...1S


      ! op_mono_data_path
      ! ~~~~~~~~~~~~~~~~~

      ! if this path is set to the empty string, '', then it defaults to the
      ! environment variable ``$(MESA_OP_MONO_DATA_PATH)``

      ! ::

    op_mono_data_path = ''      ! '' defaults to $MESA_OP_MONO_DATA_PATH


      ! op_mono_data_cache_filename
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! if this is set to the empty string, '', then it defaults to the
      ! environment variable ``$(MESA_OP_MONO_DATA_CACHE_FILENAME)``

      ! ::

    op_mono_data_cache_filename = ''      ! '' defaults to $MESA_OP_MONO_DATA_CACHE_FILENAME

      ! op_mono_method
      ! ~~~~~~~~~~~~~~

      ! Compute the Rosseland mean opacity and radiative accelerations from the OP mono data by brute force (``'hu'``)
      ! or use the faster method by allowing for a small tolerance on the mixture used for the computations of these variables (``'mombarg'``).

      ! ::

      op_mono_method = 'hu'

      ! emesh_data_for_op_mono_path
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! path to the OP_mono_master_grid_MESA_emesh.txt file containing the data need for when op_mono_method = ``'mombarg'``.
      ! If this is set to the empty string, '', then it defaults to the
      ! environment variable ``$(MESA_OP_MONO_MASTER_GRID)``

      ! You can get OP_mono_master_grid_MESA_emesh.txt from https://doi.org/10.5281/zenodo.6850861

      ! You can either download the uncompressed ``.txt`` file, or download the compressed ``.xz`` file
      ! and then unpack it in place with ``unxz -v OP_mono_master_grid_MESA_emesh.txt.xz``

      ! ::

    emesh_data_for_op_mono_path = ''      ! '' defaults to $MESA_OP_MONO_MASTER_GRID


      ! high_logT_op_mono_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! high_logT_op_mono_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! low_logT_op_mono_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! low_logT_op_mono_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! Blending controls for turning ``op_mono`` opacities off above (high_logT)
      ! and below (low_logT) specified temperature ranges.
      ! When not using ``op_mono``, the code will use standard opacity tables.
      ! For example, you might only use high T limits so that ``op_mono``
      ! is only used in the envelope, or you might set both low and
      ! high T limits so that ``op_mono`` is used around the Fe peak logT
      ! but not for other locations in the star.
      ! These controls should satisfy the following inequalities:

      ! ::

      !     high_logT_op_mono_full_off >= high_logT_op_mono_full_on
      !     high_logT_op_mono_full_on >= low_logT_op_mono_full_on
      !     low_logT_op_mono_full_on >= low_logT_op_mono_full_off

      ! op_mono opacities fully on if
      !     ``log10T`` <= ``high_logT_op_mono_full_on`` and
      !     ``log10T`` >= ``low_logT_op_mono_full_on``

      ! op_mono opacities full off if
      !     ``log10T`` >= ``high_logT_op_mono_full_off`` or
      !     ``log10T`` <= ``low_logT_op_mono_full_off``

      ! Note: OP mono ignored if either high_logT control < 0

      ! ::

    high_logT_op_mono_full_off = -99
    high_logT_op_mono_full_on = -99

      ! ::

    low_logT_op_mono_full_off = -99
    low_logT_op_mono_full_on = -99


      ! op_mono_min_X_to_include
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! skip iso if mass fraction < this

      ! ::

    op_mono_min_X_to_include = 1d-20


      ! use_op_mono_alt_get_kap
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! if true, call the ``op_mono_alt_get_kap`` routine instead of ``op_mono_get_kap``.
      ! see ``mesa/kap/public/kap_lib.f`` for details about these routines.

      ! ::

    use_op_mono_alt_get_kap = .false.

! asteroseismology controls
! =========================


      ! get_delta_nu_from_scaled_solar
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! If ``get_delta_nu_from_scaled_solar`` is ``.false.``, the
      ! large separation ``delta_nu`` is the inverse of the sound
      ! crossing time from one side of the star to the other, through
      ! the center.  This is sometimes called the "asymptotic" large
      ! separation.

      ! Otherwise, ``delta_nu`` is calculated from the asteroseismic
      ! scaling relations (see `Ulrich 1986`_, `Brown et al. 1991`_
      ! and `Kjeldsen & Bedding 1995`_) using solar reference values
      ! ``nu_max_sun``, ``delta_nu_sun`` and ``astero_Teff_sun``.

      ! ``nu_max`` is always computed from the scaling relation.

      ! .. _Ulrich 1986: https://ui.adsabs.harvard.edu/abs/1986ApJ...306L..37U
      ! .. _Brown et al. 1991:  https://ui.adsabs.harvard.edu/abs/1991ApJ...368..599B
      ! .. _Kjeldsen & Bedding 1995: https://ui.adsabs.harvard.edu/abs/1995A%26A...293...87K

      ! ::

    get_delta_nu_from_scaled_solar = .false.

      ! nu_max_sun
      ! ~~~~~~~~~~
      ! delta_nu_sun
      ! ~~~~~~~~~~~~
      ! astero_Teff_sun
      ! ~~~~~~~~~~~~~~~

      ! Solar reference values used in the asteroseismic scaling relations
      ! for ``delta_nu`` (if ``get_delta_nu_from_scaled_solar`` is ``.false.``)
      ! and ``nu_max`` (always).

      ! The default ``nu_max_sun`` is the Sun-as-as-star value reported by `Lund
      ! et al. (2017)`_, which is consistent with but conceptually
      ! different from the result of 3073.59 ± 0.18 μHz by `Kiefer et
      ! al. (2018)`_.

      ! The default ``delta_nu_sun`` is also taken from `Lund et al. (2017)`_.

      ! The default ``astero_Teff_sun`` is the value adopted in IAU 2015 Resolution B3.
      ! This should not be confused with the constant ``Teffsun``, which is always
      ! equal to the IAU value and not controlled by a parameter.  The "asteroseismic"
      ! value can be changed in case one needs to reproduce previous calculations
      ! using the scaling relations.

      ! .. _Lund et al. (2017): https://ui.adsabs.harvard.edu/abs/2017ApJ...835..172L
      ! .. _Kiefer et al. (2018): https://ui.adsabs.harvard.edu/abs/2018SoPh..293..151K

      ! ::

    nu_max_sun = 3078d0 ! μHz
    delta_nu_sun = 134.91d0 ! μHz
    astero_Teff_sun = 5772d0 ! kelvin

      ! delta_Pg_traditional
      ! ~~~~~~~~~~~~~~~~~~~~
      ! delta_Pg_mode_freq
      ! ~~~~~~~~~~~~~~~~~~

      ! For calculating the asymptotic g-mode period spacing ``delta_Pg``

      ! if ``delta_Pg_traditional`` = ``.true.``, then calculate the
      ! asymptotic gravity mode period space by directly integrating
      ! N2 over the entire stellar model.

      ! if ``delta_Pg_traditional`` = ``.false.`` use the method of
      ! `Bildsten et al. (2012) <https://ui.adsabs.harvard.edu/abs/2012ApJ...744L...6B>`_

      ! ``delta_Pg_mode_freq`` is only used when ``delta_Pg_traditional`` = ``.false.``
      ! it is provided in units of uHz. if <=0, use nu_max from scaled solar value

      ! ::

    delta_Pg_traditional = .true.
    delta_Pg_mode_freq = 0d0


   ! Brunt controls
   ! ______________


      ! calculate_Brunt_B
      ! ~~~~~~~~~~~~~~~~~
      ! calculate_Brunt_N2
      ! ~~~~~~~~~~~~~~~~~~

      ! Only calculate if this is true.

      ! ::

    calculate_Brunt_B = .true.
    calculate_Brunt_N2 = .true.


      ! brunt_N2_coefficient
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Standard N2 is multiplied by this value.

      ! ::

    brunt_N2_coefficient = 1


      ! num_cells_for_smooth_brunt_B
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Number of cells on either side to use in weighted smoothing of ``brunt_B``.

      ! ::

    num_cells_for_smooth_brunt_B = 2


      ! threshold_for_smooth_brunt_B
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Threshold for weighted smoothing of ``brunt_B``. Only apply smoothing (controlled
      ! by ``num_cells_for_smooth_brunt_B``) for contiguous regions where :math:`|B|` exceeds
      ! this threshold. Might be useful for preventing narrow peaks from being excessively
      ! broadened by smoothing

      ! ::

    threshold_for_smooth_brunt_B = 0d0


      ! min_magnitude_brunt_B
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! If set ``brunt_B`` to 0 if absolute value is < this.

      ! ::

    min_magnitude_brunt_B = -1d99


! structure equations
! ===================


      ! energy_eqn_option
      ! ~~~~~~~~~~~~~~~~~
      ! Available options are ``'dedt'`` or ``'eps_grav'``.
      ! See below for descriptions of each form and form-specific options.
      ! ::

    energy_eqn_option = 'dedt'


      ! dedt form
      ! ~~~~~~~~~

      ! This form of the energy equation is used when ``energy_eqn_option = 'dedt'``.

      ! It is a conservative equation for the local specific total energy introduced in
      ! |MESA V|, Section 3.  See in particular Eq. (8) and surrounding discussion.

      ! Because this equation is written in a conservative form, it should always do an
      ! excellent job of numerical energy conservation.  The error in numerical energy
      ! conservation (quantified by ``rel_E_err``) reflects the energy equation
      ! residuals (i.e., the extent to which the energy equation was not satisfied).
      ! When using this form of the equation, models should generally have a small
      ! (:math:`\lesssim 10^{-8}`) value of ``rel_E_err``, roughly independent of space
      ! and time resolution.  A small value of ``rel_E_err`` and its cumulative
      ! counterpart ``rel_run_E_err`` only demonstrates that the equation residuals are
      ! small and is not evidence that a model is converged or reliable.  Convergence
      ! studies targeting the physical quantities of interest remain essential.  A large
      ! value of ``rel_run_E_err`` (:math:`\gtrsim 10^{-2}`) should be a cause for
      ! concern and should be investigated further (see also
      ! :ref:`reference/controls:warn_when_large_rel_run_E_err` and
      ! :ref:`reference/controls:max_abs_rel_run_E_err` )


      ! no_dedt_form_during_relax
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! dedt_eqn_r_scale
      ! ~~~~~~~~~~~~~~~~
      ! ::

    no_dedt_form_during_relax = .true.
    dedt_eqn_r_scale = 1d8


      ! eps_grav form
      ! ~~~~~~~~~~~~~

      ! This form of the energy equation is used when ``energy_eqn_option = 'eps_grav'``.

      ! The quantity ``eps_grav`` is defined as
      ! :math:`\epsilon_{\rm grav} = -\frac{De}{Dt} - P \frac{DV_\rho}{Dt}`,
      ! where :math:`e` is the specific internal energy, :math:`P` is the pressure,
      ! :math:`V_\rho \equiv 1/\rho` is the specific volume, and :math:`D/Dt` is the
      ! Lagrangian time derivative.  See |MESA IV|, Section 8 for more discussion.

      ! This quantity is then re-written into the following convenient-to-evaluate form
      ! (see |MESA IV|, eq. 63):

      ! :math:`\epsilon_{\rm grav} = -T c_P \left[(1 - \nabla_{\rm ad} \chi_T)\frac{D\ln T}{Dt} - \nabla_{\rm ad} \chi_\rho \frac{D\ln \rho}{Dt}\right] + \epsilon_{\rm grav, X}`.

      ! The final term reflects the change in internal energy due to changes in
      ! composition (at fixed density and temperature) and is referred to in MESA as
      ! ``eps_grav_composition_term``. It is defined as

      ! :math:`\epsilon_{\rm grav, X} \equiv -\sum_i \left(\frac{\partial e}{\partial X_i}\right)_{\rho,T, \{X\ne X_i\}} \frac{DX_i}{Dt}`,

      ! and MESA evaluates this term using the finite difference

      ! :math:`\epsilon_{\rm grav, X} = -\frac{1}{\delta t}\left[e(\rho, T, X) - e(\rho, T, X_{\rm start})\right]`,

      ! where :math:`\delta t` is the timestep and :math:`X_{\rm start}` is the
      ! start-of-step mass fractions.  (Other quantities take their end-of-step values.)

      ! Note: In a phase transition, ``eps_grav`` includes the latent heat.

      ! As with the ``dedt`` form, the error in numerical energy conservation
      ! (quantified by ``rel_E_err``) reflects the energy equation residuals (i.e., the
      ! extent to which the energy equation was not satisfied).  However, because this
      ! version of the energy equation is not written in a conservative form, it also
      ! includes error associated with the time discretization.  An additional source of
      ! error enters because the equation of state provided by the ``eos`` module does
      ! not precisely satisfy the mathematical and thermodynamic identities that are
      ! used in rewriting the total and partial derivatives present in the equation.
      ! This inconsistency is usually worst at the conditions where MESA blends
      ! different component EOSes. It is important to understand that time
      ! discretization error and eos inconsistencies also affect models using the
      ! ``dedt`` form of the energy equation but manifest in different ways (e.g., as
      ! entropy generation).  Under degenerate conditions, it is often preferable to
      ! incur energy errors rather than entropy errors, and the ``eps_grav`` form should
      ! generally be preferred in such circumstances.

      ! In practice, the error sources usually exhibit the ordering
      ! (time discretization) > (eos inconsistency) >> (equation residuals).
      ! With increasing time resolution, the time discretization error can be driven
      ! down to the floor imposed by the eos inconsistency error.  The value of this
      ! floor depends on the physical conditions, but may be :math:`\sim 10^{-4}`, well
      ! above the level of the residuals (:math:`\lesssim 10^{-8}`).  The control
      ! :ref:`reference/controls:use_time_centered_eps_grav` provides a time-centered
      ! implementation of ``eps_grav`` that can often reach this floor at larger
      ! timesteps.  Convergence studies targeting the physical quantities of interest
      ! remain essential.


      ! include_composition_in_eps_grav
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, evaluate ``eps_grav_composition_term`` and include this quantity in ``eps_grav``.

      ! When this flag is true, the composition derivatives of ``eps_grav`` are also
      ! included in the Jacobian.

      ! If this flag is set to false, the ``eps_grav`` form will not conserve energy in
      ! situations with changing composition.

      ! ::

    include_composition_in_eps_grav = .true.


      ! use_time_centered_eps_grav
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, use a time-centered version of ``eps_grav`` and ``eps_grav_composition_term``.
      ! (Disabled during relax.)

      ! ::

    use_time_centered_eps_grav = .true.


      ! Gamma_lnS_eps_grav_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! Gamma_lnS_eps_grav_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Automatic switch to lnS form for eps_grav (:math:`\epsilon_{\rm grav} = -T\frac{Ds}{Dt}`) in regions with high Gamma (plasma interaction parameter).
      ! These controls only apply when using the PC EOS.  This is necessary to get the
      ! latent heat associated with the crystallization phase transition.  The
      ! composition term :math:`-\sum_i (\partial e/\partial Y_i)_{s,\rho} dY_i` is
      ! never included when the lnS form is used, independent of the setting of the
      ! control ``include_composition_in_eps_grav``.

      ! ::

    Gamma_lnS_eps_grav_full_on = 150d0
    Gamma_lnS_eps_grav_full_off = 120d0


      ! eps_grav_factor
      ! ~~~~~~~~~~~~~~~

      ! multiply eps_grav by this factor

      ! ::

    eps_grav_factor = 1d0

      ! velocity_q_upper_bound
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Local override for global ``v_flag``.
      ! If local q > this bound, local ``v_flag`` is set false,
      ! else local ``v_flag`` is set to global ``v_flag``.
      ! this lets you force v = 0 in outer envelope.

      ! ::

    velocity_q_upper_bound = 1d99

      ! velocity_tau_lower_bound
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! Local override for global ``v_flag``.
      ! If local tau < this bound, local ``v_flag`` is set false,
      ! else local ``v_flag`` is set to global ``v_flag``.
      ! this lets you force v = 0 in outer envelope.

      ! ::

    velocity_tau_lower_bound = -1d99

      ! velocity_logT_lower_bound
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Local override for global ``v_flag``.
      ! If local logT < this bound, local ``v_flag`` is set false,
      ! else local ``v_flag`` is set to global ``v_flag``.
      ! this lets you force v = 0 in outer envelope.

      ! ::

    velocity_logT_lower_bound = -1d99


      ! max_dt_yrs_for_velocity_logT_lower_bound
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Only apply ``velocity_logT_lower_bound`` when timestep < this limit.

      ! ::

    max_dt_yrs_for_velocity_logT_lower_bound = 1d99


      ! use_gravity_rotation_correction
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! With rotation, multiply gravity by ``fp_rot`` if this flag is true.
      ! See the 2nd MESA paper (2013), equation 22.
      ! previously called "use_dP_dm_rotation_correction".

      ! ::

    use_gravity_rotation_correction = .true.


      ! non_nuc_neu_factor
      ! ~~~~~~~~~~~~~~~~~~

      ! Multiplies power from non-nuclear reaction neutrinos.
      ! i.e., thermal neutrinos such as computed by mesa/neu.

      ! ::

    non_nuc_neu_factor = 1


      ! eps_nuc_factor
      ! ~~~~~~~~~~~~~~

      ! Multiplies ``eps_nuc`` without changing rates or ``dxdt_nuc``.
      ! Thus controls energy production without modifying the amount of change in abundances.

      ! ::

    eps_nuc_factor = 1


      ! eps_WD_sedimentation_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! This controls energy production from sedimentation of Ne22
      ! (and possibly other neutron-rich elements in WD interiors).

      ! ::

    eps_WD_sedimentation_factor = 1


      ! max_abs_eps_nuc
      ! ~~~~~~~~~~~~~~~

      ! Limit magnitude of eps_nuc to this.

      ! ::

    max_abs_eps_nuc = 1d99


      ! fe56ec_fake_factor
      ! ~~~~~~~~~~~~~~~~~~
      ! min_T_for_fe56ec_fake_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Hardwired small nuclear reaction network in the "approx"
      ! family treat all electron captures with a compound reaction
      ! dependent on the heaviest isotope included (see
      ! $MESA_DIR/data/net_data/nets/). The heaviest isotope
      ! determines the lowest value of ye possible in the core. The
      ! rate of the compound weak reaction is non-zero only for
      ! temperatures larger than min_T_for_fe56ec_fake_factor and is
      ! calculated multiplying the rate of electron captures on ni56
      ! by fe56ec_fake_factor. This used to be 1d-4 around MESA
      ! version 7624. Increasing this factor will push the values of
      ! ye obtained closer to the lowest possible value defined by the
      ! net, and this can be used to tune the final ye value
      ! obtainable with a small nuclear reaction network.

      ! ::

    fe56ec_fake_factor = 1d-7
    min_T_for_fe56ec_fake_factor = 3d9


      ! eps_mdot_factor
      ! ~~~~~~~~~~~~~~~

      ! multiply eps_mdot by this factor

      ! ::

    eps_mdot_factor = 1d0


      ! max_num_surf_revisions
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Max number of forced reconverges for changes in ``surf_lnS``.

      ! ::

    max_num_surf_revisions = 1


      ! max_abs_rel_change_surf_lnS
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Force solver reconverge if surf_lnS changed more than this.

      ! ::

    max_abs_rel_change_surf_lnS = 5d-4


      ! extra_power_source
      ! ~~~~~~~~~~~~~~~~~~

      ! erg/g/sec applied uniformly throughout the model
      ! This can be used to push a pre-ms model up the track to lower center temperatures.
      ! Can be used simultaneously with ``inject_extra_ergs_sec`` and ``inject_uniform_extra_heat``

      ! ::

    extra_power_source = 0


      ! inject_uniform_extra_heat
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! extra heat in erg g^-1 s^-1
      ! Added to cells in range ``min_q_for_uniform_extra_heat`` to max.
      ! Can be used simultaneously with ``inject_extra_ergs_sec`` and ``extra_power_source``.

      ! ::

    inject_uniform_extra_heat = 0


      ! min_q_for_uniform_extra_heat
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! sets bottom of region for ``inject_uniform_extra_heat``

      ! ::

    min_q_for_uniform_extra_heat = 0


      ! max_q_for_uniform_extra_heat
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! sets top of region for ``inject_uniform_extra_heat``

      ! ::

    max_q_for_uniform_extra_heat = 1


      ! inject_extra_ergs_sec
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! added to mass equal to ``grams_for_inject_extra_core_ergs_sec``
      ! can be used simultaneously with ``extra_power_source`` and ``inject_uniform_extra_heat``

      ! ::

    inject_extra_ergs_sec = 0


      ! base_of_inject_extra_ergs_sec
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! (units: Msun) sets bottom of region for ``inject_extra_ergs_sec``
      ! note: actual base is at max of this and the center of the model

      ! ::

    base_of_inject_extra_ergs_sec = 0


      ! total_mass_for_inject_extra_ergs_sec
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! (units: Msun) sets size of region for ``inject_extra_ergs_sec``

      ! ::

    total_mass_for_inject_extra_ergs_sec = 0


      ! start_time_for_inject_extra_ergs_sec
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! (units: sec) start time for injecting extra ergs/s

      ! ::

    start_time_for_inject_extra_ergs_sec = -1d99


      ! duration_for_inject_extra_ergs_sec
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! (units: sec) length of time for injecting extra ergs/s
      ! set to negative value to keep injecting indefinitely or until reach target

      ! ::

    duration_for_inject_extra_ergs_sec = -1


      ! inject_until_reach_model_with_total_energy
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! (units: ergs) target for model total energy
      ! usually want to set ``duration_for_inject_extra_ergs_sec = -1`` for this option.
      ! continue injecting until total energy of model reaches min of
      ! ``inject_until_reach_model_with_total_energy``, and
      ! ``initial total energy``

      ! ::

    inject_until_reach_model_with_total_energy = 1d99

      ! steps_before_use_velocity_time_centering
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! include_P_in_velocity_time_centering
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! include_L_in_velocity_time_centering
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! use_P_d_1_div_rho_form_of_work_when_time_centering_velocity
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! P_theta_for_velocity_time_centering
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! L_theta_for_velocity_time_centering
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_logT_for_include_P_and_L_in_velocity_time_centering
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! for time weighting in energy and momentum equations
      ! to give intrinsic conservation of total energy (conservation -> perfect as residuals -> 0),
      ! and to minimize numerical damping.
      ! as discussed in the 3rd mesa instrument paper (2015).
      ! time centering applies to velocities, pressures, and luminosities.
      ! not for u_flag.
      ! steps_before_use_velocity_time_centering < 0 means no time centering.
      ! P_theta and L_theta = 0.5 for time centered, = 1.0 for fully implicit.
      ! Above ``max_logT_for_include_P_and_L_in_velocity_time_centering``, P and L are not time centered
      ! to aid in damping spurious modes in the core.

      ! ::

    steps_before_use_velocity_time_centering = -1
    include_P_in_velocity_time_centering = .false.
    P_theta_for_velocity_time_centering = 0.5d0
    include_L_in_velocity_time_centering = .false.
    L_theta_for_velocity_time_centering = 0.5d0
    use_P_d_1_div_rho_form_of_work_when_time_centering_velocity = .false.
    max_logT_for_include_P_and_L_in_velocity_time_centering = 1d99

      ! use_dPrad_dm_form_of_T_gradient_eqn
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! use_flux_limiting_with_dPrad_dm_form
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! use_gradT_actual_vs_gradT_MLT_for_T_gradient_eqn
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_kap_for_dPrad_dm_eqn
      ! ~~~~~~~~~~~~~~~~~~~~~~~~


      ! These are for alternatives ways to determine the T gradient.
      ! The standard form of the equation is

      !     dT/dm = dP/dm * T/P * grad_T, grad_T = dlnT/dlnP from MLT.

      ! use hydrostatic value for dP/dm in this.
      ! this is because of limitations of MLT for calculating grad_T.
      ! (MLT assumes hydrostatic equilibrium)
      ! see comment in K&W chpt 9.1.

      ! The alternatives forms are for dynamic situations where
      ! the use of hydrostatic dP/dm is inappropriate.
      ! In order of priority,

      !|     if (use_gradT_actual_vs_gradT_MLT_for_T_gradient_eqn)
      !|        equation is gradT(k)*(lnPeos(k-1) - lnPeos(k)) = lnT(k-1) - lnT(k)
      !|     recall that gradT(k) is expected dlnT/dlnPeos at face k from MLT.
      !|
      !|     if (use_dPrad_dm_form_of_T_gradient_eqn)
      !|         if (gradT < gradr) then
      !|            use L_rad = L*gradT/gradr (see, e.g., Cox&Giuli 14.109)
      !|         else
      !|            use L_rad = L
      !|     if (use_flux_limiting_with_dPrad_dm_form)
      !|         flxR = 4 * pi * r^2 * abs(dT^4/dm) / kap
      !|         flxLambda = (6 + 3*flxR) / (6 + 3*flxR + flxR^2) (see Levermore & Pomraning 1981)
      !|         L_rad = L_rad / flxLambda
      !|

      ! With the resulting ``L_rad``, determine the expected dT/dm by

      !     d_Prad/dm = -kap*L_rad/(clight*area^2) -- see, e.g., K&W (5.12)

      ! ::

    use_dPrad_dm_form_of_T_gradient_eqn = .false.
    min_kap_for_dPrad_dm_eqn = 1d-4
    use_flux_limiting_with_dPrad_dm_form = .false.
    use_gradT_actual_vs_gradT_MLT_for_T_gradient_eqn = .false.


! Hydrodynamic drag
! =================

      ! use_drag_energy
      ! ~~~~~~~~~~~~~~~
      ! drag_coefficient
      ! ~~~~~~~~~~~~~~~~
      ! min_q_for_drag
      ! ~~~~~~~~~~~~~~

      ! only when v_flag = .true.. Adjusts both v and energy transfer from kinetic to thermal.
      ! only for v(k) when q(k) > min_q_for_drag.
      ! kill off fraction of v = drag_coefficient (i.e. set to 1 to keep v near 0)
      ! useful for preventing the development radial pulsations during advanced
      ! burning in massive stars and AGB stars.

      ! Under certain circumstances we will not have drag in the surface k=1 zone
      ! To force the drag term to be on in the outer zone you must enable one of the
      ! following surface boundary conditions:
      ! ``use_momentum_outer_BC``, ``use_zero_Pgas_outer_BC``, or ``use_fixed_Psurf_outer_BC``

      ! If use_drag_energy = .true. adds the work done by the drag force
      ! to the energy balance. Since the drag force is proportional to
      ! the velocity which is subject to numerical spikes and
      ! oscillations, you may not want to use the work done by it in the
      ! model If set to .false. but drag_coefficient is nonzero, the
      ! drag force will be applied in the momentum equation (as a
      ! numerical trick to damp spurious velocities) but not in the
      ! energy equation.

      ! ::

    use_drag_energy = .true.
    drag_coefficient = 0d0
    min_q_for_drag = 0d0


      ! v_drag_factor
      ! ~~~~~~~~~~~~~
      ! v_drag
      ! ~~~~~~
      ! q_for_v_drag_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! q_for_v_drag_full_on
      ! ~~~~~~~~~~~~~~~~~~~~


      ! Only when u_flag = .true.. Adds a pseudo drag term of the form
      ! -v_drag_factor*(v-v_drag)^2/r, can be used damp velocities in outer layers
      ! of a star, useful for smoothing out spurious shocks colliding in ejected layers.
      ! Effect is full on for q>q_for_v_drag_full_on and full off for
      ! q < q_for_v_drag_full_off.

      ! ::

    v_drag_factor = 0d0
    v_drag = 0d0
    q_for_v_drag_full_off = 0.95d0
    q_for_v_drag_full_on = 0.96d0


      ! Rayleigh-Taylor Instability: hydro drag terms
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! for hydro comparison tests (e.g., Sedov)

      ! RTI_A
      ! ~~~~~
      ! RTI_B
      ! ~~~~~
      ! RTI_C
      ! ~~~~~
      ! RTI_D
      ! ~~~~~
      ! RTI_C_X0_frac
      ! ~~~~~~~~~~~~~
      ! RTI_C_X_factor
      ! ~~~~~~~~~~~~~~
      ! RTI_max_alpha
      ! ~~~~~~~~~~~~~
      ! RTI_min_dm_behind_shock_for_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! RTI_dm_for_center_eta_nondecreasing
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! RTI_energy_floor
      ! ~~~~~~~~~~~~~~~~
      ! RTI_D_mix_floor
      ! ~~~~~~~~~~~~~~~
      ! RTI_min_m_for_D_mix_floor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! RTI_log_max_boost
      ! ~~~~~~~~~~~~~~~~~
      ! RTI_m_full_boost
      ! ~~~~~~~~~~~~~~~~
      ! RTI_m_no_boost
      ! ~~~~~~~~~~~~~~

      ! Note that these parameters are not exactly the same
      ! as used by Paul Duffell.
      ! His calibrated D is 2, where mesa has default D = 3 (see |MESA IV|).
      ! Users should try various values since the choice is not clear cut.

      ! ::

    RTI_A = 1d-3
    RTI_B = 2.5d0
    RTI_C = 0.2d0
    RTI_D = 3d0

      ! ::

    RTI_C_X0_frac = 0.9d0
    RTI_C_X_factor = 0d0

      ! ::

    RTI_max_alpha = 0.5d0
    RTI_min_dm_behind_shock_for_full_on = 0d0
    RTI_dm_for_center_eta_nondecreasing = 0.02d0
    RTI_energy_floor = 0d0
    RTI_D_mix_floor = 0d0
    RTI_min_m_for_D_mix_floor = 0d0

      ! ::

    RTI_log_max_boost = 3d0
    RTI_m_full_boost = 4d0
    RTI_m_no_boost = 5d0


      ! retry_for_v_above_clight
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! If .true., a retry will be triggered at the end of a step
      ! if the maximum velocity exceeds the speed of light.
      ! If .false., only a warning is printed.

      ! ::

    retry_for_v_above_clight = .true.


! solver controls
! ===============

      ! the following is from a response on mesa-users to a question about controls
      ! for solver tolerances:

      ! The "residual" is the left over difference between the left and right hand sides
      ! of the equation we are trying to solve.  We do iterations to reduce that, but we
      ! are limited by the non-linearity of the problem and the quality of the estimates
      ! for the derivatives.

      ! The "correction" is the change in the primary variable that is calculated using
      ! good-old Newton's rule in multiple dimensions --- so Jacobian and residuals give
      ! a correction that would make the next residual vanish if the problem were linear
      ! and the Jacobian was exact, neither of which are true.  So the best we can hope
      ! for is that the corrections will get smaller next time.

      ! The "norm" is the average; the "max" is the max. Sometimes you mainly care about
      ! the norm and will accept a few outliers. But sometimes you don't want any really
      ! bad outliers, so you want to set a low limit for the max residual or correction
      ! as well as the norm.

      ! You might want to try for several iterations with strict tolerances, and then
      ! relax them if things are still not converged.  For example, you might be willing
      ! to live with the larger tolerances, but you'd like to give it a good try at the
      ! smaller ones before switching. Also, you might be willing to settle for any-old
      ! residual if the corrections have become small enough. You can do that too by
      ! relaxing the residual tolerances after a few iterations.

      ! Hope that at least helps with the nomenclature.

      ! I agree with Frank that you should consider the effects of smaller timesteps and
      ! more grid points as your main technique --- tightening up the tolerances for the
      ! solver won't help if you are taking timesteps that are too large or if you have
      ! inadequate grid resolution.


      ! tol_correction_norm
      ! ~~~~~~~~~~~~~~~~~~~
      ! tol_max_correction
      ! ~~~~~~~~~~~~~~~~~~

      ! "Correction" for variable x(i,k) is scaled change, dx(i,k)/xscale(i,k).
      ! these tolerances are for the magnitude of the scaled corrections.

      ! ::

    tol_correction_norm = 3d-5
    tol_max_correction = 3d-3


      ! tol_correction_high_T_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! For very late stages of massive star evolution, need to relax tolerances.
      ! If max T >= this limit, switch scaling factors.

      ! ::

    tol_correction_high_T_limit = 1d9


      ! tol_correction_norm_high_T
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! tol_max_correction_high_T
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Above ``tol_correction_high_T_limit`` use these scaling factors.

      ! ::

    tol_correction_norm_high_T = 3d-3
    tol_max_correction_high_T = 3d-1


      ! tol_correction_extreme_T_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! For very late stages of massive star evolution, need to relax tolerances.
      ! If center T >= this limit, switch scaling factors.

      ! ::

    tol_correction_extreme_T_limit = 6d9


      ! tol_correction_norm_extreme_T
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! tol_max_correction_extreme_T
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! For very late stages of massive star evolution, need to relax tolerances.
      ! If center T >= this limit, switch scaling factors.

      ! ::

    tol_correction_norm_extreme_T = 8d-3
    tol_max_correction_extreme_T = 8d-1


      ! tol_bad_max_correction
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! if ``max_correction > tol_max_correction`` and no more iterations allowed,
      ! then still accept the solution if ``max_correction <= tol_bad_max_correction``.
      ! but if ``max_correction > tol_bad_max_correction``, then reject the solution.

      ! ::

    tol_bad_max_correction = 0d0


      ! bad_max_correction_series_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If have this many steps in a row with ``max_correction > tol_max_correction``,
      ! then do a retry with a smaller timestep.

      ! ::

    bad_max_correction_series_limit = 2


      ! relax_use_gold_tolerances
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    relax_use_gold_tolerances = .false.


      ! relax_solver_iters_timestep_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! relax_tol_correction_norm
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! relax_tol_max_correction
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! relax_tol_residual_norm1
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! relax_tol_max_residual1
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! relax_iter_for_resid_tol2
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! relax_tol_residual_norm2
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! relax_tol_max_residual2
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! relax_iter_for_resid_tol3
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! relax_tol_residual_norm3
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! relax_tol_max_residual3
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! relax_maxT_for_gold_tolerances
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! For use during relax operations.   Only used if /= 0.

      ! ::

    relax_solver_iters_timestep_limit = 0

      ! ::

    relax_tol_correction_norm = 0d0
    relax_tol_max_correction = 0d0

      ! ::

    relax_tol_residual_norm1 = 0d0
    relax_tol_max_residual1 = 0d0
    relax_iter_for_resid_tol2 = 3

      ! ::

    relax_tol_residual_norm2 = 0d0
    relax_tol_max_residual2 = 0d0
    relax_iter_for_resid_tol3 = 0

      ! ::

    relax_tol_residual_norm3 = 0d0
    relax_tol_max_residual3 = 0d0
    relax_maxT_for_gold_tolerances = -1d0


      ! include_L_in_correction_limits
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! include_v_in_correction_limits
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! include_u_in_correction_limits
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! include_w_in_correction_limits
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! These variables can be excluded from calculation of correction norm and max.

      ! ::

    include_L_in_correction_limits = .true.
    include_v_in_correction_limits = .true.
    include_u_in_correction_limits = .true.
    include_w_in_correction_limits = .true.


      ! max_X_for_conv_timescale
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_X_for_conv_timescale
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_q_for_conv_timescale
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_q_for_conv_timescale
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_q_for_QHSE_timescale
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_q_for_QHSE_timescale
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    max_X_for_conv_timescale = 1d0
    min_X_for_conv_timescale = 0d0
    max_q_for_conv_timescale = 1d0
    min_q_for_conv_timescale = 0d0
    max_q_for_QHSE_timescale = 1d0
    min_q_for_QHSE_timescale = 0d0


      ! correction_xa_limit
      ! ~~~~~~~~~~~~~~~~~~~

      ! Ignore correction to abundance when calculating correction norm and max
      ! if current mass fraction is less than this limit.

      ! ::

    correction_xa_limit = 5d-3


      ! xa_scale
      ! ~~~~~~~~

      ! Scaling for abundance variables is ``max(xa_scale, current mass fraction)``.

      ! ::

    xa_scale = 1d-5


      ! tol_residual_norm1
      ! ~~~~~~~~~~~~~~~~~~
      ! tol_max_residual1
      ! ~~~~~~~~~~~~~~~~~
      ! iter_for_resid_tol2
      ! ~~~~~~~~~~~~~~~~~~~

      ! "residual" for equation is the difference between left and right sides
      ! use ``tol_residual_norm1`` & ``tol_max_residual1``
      ! at iteration number ``iter_for_resid_tol2``, switch to next tolerances.

      ! ::

    tol_residual_norm1 = 1d-10
    tol_max_residual1 = 1d-9
    iter_for_resid_tol2 = 6


      ! tol_residual_norm2
      ! ~~~~~~~~~~~~~~~~~~
      ! tol_max_residual2
      ! ~~~~~~~~~~~~~~~~~
      ! iter_for_resid_tol3
      ! ~~~~~~~~~~~~~~~~~~~

      ! Use ``tol_residual_norm2`` & ``tol_max_residual2``
      ! these apply starting at iteration number ``iter_for_resid_tol2``.
      ! at iteration number ``iter_for_resid_tol3``, switch to next tolerances.

      ! ::

    tol_residual_norm2 = 1d90
    tol_max_residual2 = 1d90
    iter_for_resid_tol3 = 15


      ! tol_residual_norm3
      ! ~~~~~~~~~~~~~~~~~~
      ! tol_max_residual3
      ! ~~~~~~~~~~~~~~~~~

      ! Use ``tol_residual_norm3`` & ``tol_max_residual3``
      ! these apply starting at iteration number ``iter_for_resid_tol3``.

      ! ::

    tol_residual_norm3 = 1d90
    tol_max_residual3 = 1d90

      ! If things get worse from one iteration to next, give up.
      ! The following are the limits that define "getting worse enough to stop".


      ! corr_norm_jump_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If correction norm increases by this factor or more, quit.

      ! ::

    corr_norm_jump_limit = 1d99


      ! max_corr_jump_limit
      ! ~~~~~~~~~~~~~~~~~~~

      ! If correction max increases by this factor or more, quit.

      ! ::

    max_corr_jump_limit = 1d12


      ! resid_norm_jump_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! If residual norm increases by this factor or more, quit.

      ! ::

    resid_norm_jump_limit = 1d99


      ! max_resid_jump_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If residual max increases by this factor or more, quit.

      ! ::

    max_resid_jump_limit = 1d12


      ! convergence_ignore_equL_residuals
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    convergence_ignore_equL_residuals = .false.

      ! convergence_ignore_alpha_RTI_residuals
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    convergence_ignore_alpha_RTI_residuals = .false.


      ! trace_solver_damping
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Send solver damping data to screen.

      ! ::

    trace_solver_damping = .false.

      ! do_normalize_dqs_as_part_of_set_qs
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! normalize_dqs destroys bit-for-bit read as inverse of write for models.
      ! ok for create pre ms etc., but not for read model
      ! create_pre_ms calls normalize_dqs even if this flag is false.

      ! ::

   do_normalize_dqs_as_part_of_set_qs = .false.


      ! use_DGESVX_in_bcyclic
      ! use_equilibration_in_DGESVX
      ! report_min_rcond_from_DGESXV

      ! FOR DEBUGGING ONLY.   NOT FOR GENERAL USE.

      ! ::

    use_DGESVX_in_bcyclic = .false.
    use_equilibration_in_DGESVX = .false.
    report_min_rcond_from_DGESXV = .false.


      ! solver_max_tries_before_reject
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Max number solver iterations before give up.

      ! ::

    solver_max_tries_before_reject = 25


      ! max_tries1
      ! ~~~~~~~~~~

      ! Max tries on 1st model.

      ! ::

    max_tries1 = 250


      ! max_tries_for_retry
      ! ~~~~~~~~~~~~~~~~~~~

      ! Normal number of retries.

      ! ::

    max_tries_for_retry = 25


      ! max_tries_after_5_retries
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Increase number of tries after 5 failed ones.

      ! ::

    max_tries_after_5_retries = 35


      ! max_tries_after_10_retries
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Increase number of tries after 10 failed ones.

      ! ::

    max_tries_after_10_retries = 50


      ! max_tries_after_20_retries
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Increase number of tries after 20 failed ones.

      ! ::

    max_tries_after_20_retries = 75


      ! retry_limit
      ! ~~~~~~~~~~~

      ! Only use if > 0.
      ! In case the solver fails for some reason, it will retry with a smaller timestep.
      ! It does up to this many retries for the current step before terminating.

      ! ::

    retry_limit = 100


      ! redo_limit
      ! ~~~~~~~~~~

      ! Only use if > 0.
      ! Do up to this many redo's for the current step before terminating.

      ! ::

    redo_limit = 100


      ! solver_itermin
      ! ~~~~~~~~~~~~~~

      ! Use at least this many iterations in solver for hydro solve.

      ! ::

    solver_itermin = 2


      ! solver_itermin_until_reduce_min_corr_coeff
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Use at least this many iterations in solver
      ! before try using small ``min_corr_coeff``

      ! ::

    solver_itermin_until_reduce_min_corr_coeff = 8


      ! solver_reduced_min_corr_coeff
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! For use with ``solver_itermin_for_reduce_min_corr_coeff``.

      ! ::

    solver_reduced_min_corr_coeff = 0.1d0


      ! tiny_corr_coeff_limit
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! scale_correction_norm
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! corr_param_factor
      ! ~~~~~~~~~~~~~~~~~
      ! scale_max_correction
      ! ~~~~~~~~~~~~~~~~~~~~
      ! ignore_too_large_correction
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! corr_coeff_limit
      ! ~~~~~~~~~~~~~~~~
      ! tiny_corr_factor
      ! ~~~~~~~~~~~~~~~~
      ! ignore_min_corr_coeff_for_scale_max_correction
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! ignore_species_in_max_correction
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! num_times_solver_reuse_mtx
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! see star/private/star_solver for info about these

      ! ::

    tiny_corr_coeff_limit = 100
    scale_correction_norm = 0.1d0
    corr_param_factor = 10
    scale_max_correction = 1d99
    ignore_too_large_correction = .false.
    corr_coeff_limit = 1d-2
    tiny_corr_factor = 2
    ignore_min_corr_coeff_for_scale_max_correction = .false.
    ignore_species_in_max_correction = .false.
    num_times_solver_reuse_mtx = 0


      ! min_xa_hard_limit
      ! ~~~~~~~~~~~~~~~~~
      ! min_xa_hard_limit_for_highT
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If solver produces mass fraction < this limit,
      ! then reject the trial solution.
      ! Can optionally relax this limit at high T.

      ! ::

    min_xa_hard_limit = -1d-5
    min_xa_hard_limit_for_highT = -3d-5


      ! logT_max_for_min_xa_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Use ``min_xa_hard_limit`` for center logT <= this.

      ! ::

    logT_max_for_min_xa_hard_limit = 9.49d0


      ! logT_min_for_min_xa_hard_limit_for_highT
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Use ``min_xa_hard_limit_for_highT`` for center logT >= this.
      ! Linear interpolate in logT for intermediate center temperatures.

      ! ::

    logT_min_for_min_xa_hard_limit_for_highT = 9.51d0


      ! sum_xa_hard_limit
      ! ~~~~~~~~~~~~~~~~~
      ! sum_xa_hard_limit_for_highT
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If solver produces any cell with abs(sum(xa)-1) > this limit,
      ! then reject the trial solution.
      ! Can optionally relax this limit at high T.

      ! ::

    sum_xa_hard_limit = 5d-4
    sum_xa_hard_limit_for_highT = 1d-3


      ! logT_max_for_sum_xa_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Use ``sum_xa_hard_limit`` for center logT <= this.

      ! ::

    logT_max_for_sum_xa_hard_limit = 9.40d0


      ! logT_min_for_sum_xa_hard_limit_for_highT
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Use ``sum_xa_hard_limit_for_highT`` for center logT >= this.
      ! Linear interpolate in logT for intermediate center temperatures.

      ! ::

    logT_min_for_sum_xa_hard_limit_for_highT = 9.44d0


      ! do_solver_damping_for_neg_xa
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, uniformly reduce solver corrections if necessary to avoid neg abundances.

      ! ::

    do_solver_damping_for_neg_xa = .true.


      ! scale_max_correction_for_negative_surf_lum
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_frac_for_negative_surf_lum
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, then scales the correction factor in a Newton iteration to prevent the
      ! surface from reaching a negative luminosity. If an iteration would require s% L(1)
      ! to become negative, then the correction is scaled such that the change in surface
      ! luminosity is -max_frac_for_negative_surf_lum*s% L(1)

      ! ::

    scale_max_correction_for_negative_surf_lum = .false.
    max_frac_for_negative_surf_lum = 0.8


      ! min_chem_eqn_scale
      ! ~~~~~~~~~~~~~~~~~~

      ! ::

    min_chem_eqn_scale = 1d0


      ! hydro_mtx_max_allowed_{abs}{dlogT | dlogRho | logT | logRho}
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Force retry with smaller timestep if hydro solves change T or Rho by too much
      ! or make them too large.

      ! ::

    hydro_mtx_max_allowed_abs_dlogT = 99d0
    hydro_mtx_max_allowed_abs_dlogRho = 99d0
    min_logT_for_hydro_mtx_max_allowed = -1d99
    hydro_mtx_max_allowed_logT = 12d0
    hydro_mtx_max_allowed_logRho = 12d0

      ! ::

    hydro_mtx_min_allowed_logT = 1d0
    hydro_mtx_min_allowed_logRho = -1d2

      ! level 1 of gold tolerances for solver solver


      ! use_gold_tolerances
      ! ~~~~~~~~~~~~~~~~~~~
      ! steps_before_use_gold_tolerances
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! gold_solver_iters_timestep_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! maxT_for_gold_tolerances
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! gold_tol_residual_norm1
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! gold_tol_max_residual1
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! gold_iter_for_resid_tol2
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! gold_tol_residual_norm2
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! gold_tol_max_residual2
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! gold_iter_for_resid_tol3
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! gold_tol_residual_norm3
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! gold_tol_max_residual3
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    use_gold_tolerances = .true.
    steps_before_use_gold_tolerances = -1

      ! if >= 0, then after this many steps in run, act as if use_gold_tolerances true
      ! this allows a delay before turning on gold tolerances
      ! NOTE: if using steps_before_use_gold_tolerances >= 0, then set use_gold_tolerances = false

      ! ::

    maxT_for_gold_tolerances = 1d99

      ! ::

    gold_tol_residual_norm1 = 1d-11
    gold_tol_max_residual1 = 1d-9
    gold_iter_for_resid_tol2 = 5
    gold_tol_residual_norm2 = 1d-8
    gold_tol_max_residual2 = 1d-6
    gold_iter_for_resid_tol3 = 10
    gold_tol_residual_norm3 = 1d-6
    gold_tol_max_residual3 = 1d-4

      ! ::

    gold_solver_iters_timestep_limit = 14

      ! level 2 of gold tolerances for solver solver - tighter than level 1


      ! use_gold2_tolerances
      ! ~~~~~~~~~~~~~~~~~~~~
      ! steps_before_use_gold2_tolerances
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! gold2_solver_iters_timestep_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! gold2_tol_residual_norm1
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! gold2_tol_max_residual1
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! gold2_iter_for_resid_tol2
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! gold2_tol_residual_norm2
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! gold2_tol_max_residual2
      ! ~~~~~~~~~~~~~~~~~~~~~~~
      ! gold2_iter_for_resid_tol3
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! gold2_tol_residual_norm3
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! gold2_tol_max_residual3
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    use_gold2_tolerances = .false.
    steps_before_use_gold2_tolerances = -1

      ! if >= 0, then after this many steps in run, act as if use_gold2_tolerances true
      ! this allows a delay before turning on level 2 gold tolerances
      ! NOTE: if using steps_before_use_gold2_tolerances >= 0, then set use_gold2_tolerances = false

      ! ::

    gold2_tol_residual_norm1 = 1d-11
    gold2_tol_max_residual1 = 1d-9
    gold2_iter_for_resid_tol2 = 5
    gold2_tol_residual_norm2 = 1d-10
    gold2_tol_max_residual2 = 1d-8
    gold2_iter_for_resid_tol3 = 10
    gold2_tol_residual_norm3 = 1d-8
    gold2_tol_max_residual3 = 1d-5

      ! ::

    gold2_solver_iters_timestep_limit = 18


      ! include_rotation_in_total_energy
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! previously called ``include_rotation_in_energy_error_report``

      ! ::

    include_rotation_in_total_energy = .false.

      ! artificial viscosity


      ! use_Pvsc_art_visc
      ! ~~~~~~~~~~~~~~~~~
      ! Pvsc_cq
      ! ~~~~~~~
      ! Pvsc_zsh
      ! ~~~~~~~~

      ! Pvsc is artificial pressure to push back against compression
      ! this is the form of artificial viscosity used in RSP
      ! if using this, do not set use_artificial_viscosity true.

      ! artificial viscosity controls
      ! for the equations see: Appendix C in
      ! `Stellingwerf (1975) <https://ui.adsabs.harvard.edu/abs/1975ApJ...195..441S>`_
      ! In principle, for not too-non-adiabatic convective models artificial viscosity is not
      ! needed or should be very small. Hence a large cut-off parameter below (in purely
      ! radiative models the default value for cut-off was 0.01)

      ! zsh > 0 delays onset of artificial viscosity
      ! can eliminate most/all interior dissipation while still providing for extreme cases.
      ! using this parameter the dependence of limiting amplitude on cq is very weak.

      ! ::

    use_Pvsc_art_visc = .false.
    Pvsc_cq = 4.0d0
    Pvsc_zsh = 0.1d0


      ! use_artificial_viscosity
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! use_artificial_viscosity has been replaced by use_Pvsc_art_visc.

! split burn
! ==========


      ! op_split_burn
      ! ~~~~~~~~~~~~~

      ! ::

    op_split_burn = .false.


      ! op_split_burn_min_T
      ! ~~~~~~~~~~~~~~~~~~~
      ! op_split_burn_eps
      ! ~~~~~~~~~~~~~~~~~
      ! op_split_burn_odescal
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Only do op_split_burn in cells with T >= this limit at start of step.

      ! ::

    op_split_burn_min_T = 2d9
    op_split_burn_eps = 1d-5
    op_split_burn_odescal = 1d-5


      ! op_split_burn_eps_nuc_infall_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! turn off ``op_split_burn`` nuclear burning if max infall speed exceeds this limit (cm/s).

      ! ::

    op_split_burn_eps_nuc_infall_limit = 1d99

! timestep controls
! =================

      ! The terminal output during evolution includes a short string for the ``dt_limit``.
      ! This is to give you some indication of what is limiting the time steps.
      ! Here's a dictionary mapping those terminal strings to the corresponding control parameters.
      ! (There is a similar table in ``mesa/binary/defaults/binary_controls.defaults``.)

      ! ::

      !           terminal output       related parameter
      !          'burn steps'           burn_steps_limit
      !          'Lnuc'                 delta_lgL_nuc_limit
      !          'Lnuc_cat'             delta_lgL_nuc_cat_limit
      !          'Lnuc_H'               delta_lgL_H_limit
      !          'Lnuc_He'              delta_lgL_He_limit
      !          'lgL_power_phot'       delta_lgL_power_photo_limit
      !          'Lnuc_z'               delta_lgL_z_limit
      !          'bad_X_sum'            (solver found bad mass sum)
      !          'dL/L'                 dL_div_L_limit
      !          'dX'                   dX_limit
      !          'dX/X'                 dX_div_X_limit
      !          'dX_nuc_drop'          dX_nuc_drop_limit
      !          'delta mdot'           delta_mdot_limit
      !          'delta total J'        delta_lg_total_J_limit
      !          'delta_HR'             delta_HR_limit
      !          'delta_mstar'          delta_lg_star_mass_limit
      !          'diff iters'           diffusion_iters_limit
      !          'diff steps'           diffusion_steps_limit
      !          'min_dr_div_cs'        dt_div_min_dr_div_cs_limit
      !          'dt_collapse'          dt_div_dt_cell_collapse_limit
      !          'eps_nuc_cntr'         delta_log_eps_nuc_cntr_limit
      !          'error rate'           limit_for_log_rel_rate_in_energy_conservation
      !          'highT del Ye'         delta_Ye_highT_limit
      !          'hold'                 (recent retry, so no increase in dt)
      !          'lgL'                  delta_lgL_limit
      !          'lgP'                  delta_lgP_limit
      !          'lgP_cntr'             delta_lgP_cntr_limit
      !          'lgR'                  delta_lgR_limit
      !          'lgRho'                delta_lgRho_limit
      !          'lgRho_cntr'           delta_lgRho_cntr_limit
      !          'lgT'                  delta_lgT_limit
      !          'lgT_cntr'             delta_lgT_cntr_limit
      !          'lgT_max'              delta_lgT_max_limit
      !          'lgT_max_hi_T'         delta_lgT_max_at_high_T_limit
      !          'lgTeff'               delta_lgTeff_limit
      !          'dX_div_X_cntr'        delta_dX_div_X_cntr_limit
      !          'lg_XC_cntr'           delta_lg_XC_cntr_limit
      !          'lg_XH_cntr'           delta_lg_XH_cntr_limit
      !          'lg_XHe_cntr'          delta_lg_XHe_cntr_limit
      !          'lg_XNe_cntr'          delta_lg_XNe_cntr_limit
      !          'lg_XO_cntr'           delta_lg_XO_cntr_limit
      !          'lg_XSi_cntr'          delta_lg_XSi_cntr_limit
      !          'XC_cntr'              delta_XC_cntr_limit
      !          'XH_cntr'              delta_XH_cntr_limit
      !          'XHe_cntr'             delta_XHe_cntr_limit
      !          'XNe_cntr'             delta_XNe_cntr_limit
      !          'XO_cntr'              delta_XO_cntr_limit
      !          'XSi_cntr'             delta_XSi_cntr_limit
      !          'log_eps_nuc'          delta_log_eps_nuc_limit
      !          'max_dt'               max_years_for_timestep
      !          'neg_mass_frac'        (solver found neg mass frac)
      !          'adjust_J_q'           adjust_J_q_limit
      !          'solver iters'         solver_iters_timestep_limit
      !          'rel_E_err'            limit_for_rel_error_in_energy_conservation
      !          'varcontrol'           varcontrol_target
      !          'max increase'         max_timestep_factor or max_timestep_factor_at_high_T
      !          'max decrease'         min_timestep_factor
      !          'retry'                (just did a retry)
      !          'b_****'               see binary/defaults/binary_controls.defaults


      ! time_delta_coeff
      ! ~~~~~~~~~~~~~~~~

      ! time_delta_coeff - smaller forces smaller timesteps giving better time resolution.
      ! multiplier for all real number timestep limits and hard limits.
      ! does not apply to integer valued limits such as

      ! + solver_iters_timestep_limit
      ! + burn_steps_limit
      ! + diffusion_steps_limit
      ! + diffusion_iters_limit

      ! does not apply to varcontrol_target.
      ! analogous to mesh_delta_coeff for better spatial resolution.

      ! ::

    time_delta_coeff = 1d0


      ! max_timestep
      ! ~~~~~~~~~~~~

      ! In seconds.  ``max_timestep <= 0`` means no upper limit.

      ! ::

    max_timestep = 0


      ! max_years_for_timestep
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! ``max_years_for_timestep <= 0`` means no upper limit.
      ! Note: ``max_timestep`` is the control that is used by most of the code.
      ! ``max_years_for_timestep`` is just provided as a convenience.
      ! At the start of each step, the evolve routine checks to see if ``max_years_for_timestep > 0``,
      ! and if so, it sets ``max_timestep = max_years_for_timestep*secyer``.

      ! ::

    max_years_for_timestep = 0


      ! max_timestep_hi_T_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! If ``max T >= this``, then switch to ``hi_T_max_years_for_timestep``.
      ! Ignore if <= 0.

      ! ::

    max_timestep_hi_T_limit = -1


      ! hi_T_max_years_for_timestep
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Max years for timestep if ``max_timestep_hi_T_limit`` is active.

      ! ::

    hi_T_max_years_for_timestep = 0


      ! min_timestep_factor
      ! ~~~~~~~~~~~~~~~~~~~

      ! Lower limit for ratio of new timestep to previous timestep.
      ! i.e., allow dt to get smaller by no more than this factor -- 0 means no limit.

      ! ::

    min_timestep_factor = 0.8d0


      ! force_timestep
      ! ~~~~~~~~~~~~~~

      ! In seconds.  ``force_timestep <= 0`` means no forced timestep.

      ! ::

    force_timestep = 0


      ! force_timestep_years
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Note: ``force_timestep`` is the control that is used by most of the code.
      ! ``force_timestep_years`` is just provided as a convenience.
      ! At the start of each step, the evolve routine checks if ``force_timestep_years > 0``,
      ! and if so, it sets ``force_timestep = force_timestep_years*secyer``.

      ! ::

    force_timestep_years = 0


      ! force_timestep_min
      ! ~~~~~~~~~~~~~~~~~~

      ! In seconds.  ``force_timestep_min <= 0`` means no forced lower limit.

      ! ::

    force_timestep_min = 0


      ! force_timestep_min_years
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! Note: ``force_timestep_min`` is the control that is used by most of the code.
      ! ``force_timestep_min_years`` is just provided as a convenience.
      ! At the start of each step, the evolve routine checks if ``force_timestep_min_years > 0``,
      ! and if so, it sets ``force_timestep_min = force_timestep_min_years*secyer``.

      ! ::

    force_timestep_min_years = 0


      ! force_timestep_min_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If dt is < ``force_timestep_min``, then
      ! replace dt by ``min(dt*force_timestep_min_factor, force_timestep_min)``

      ! ::

    force_timestep_min_factor = 2d0


      ! max_timestep_factor
      ! ~~~~~~~~~~~~~~~~~~~
      ! max_timestep_factor_at_high_T
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_logT_for_max_timestep_factor_at_high_T
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Upper limit for ratio of new timestep to previous timestep.
      ! i.e., allow dt to get larger by no more than this factor -- 0 means no limit.
      ! use ``max_timestep_factor_at_high_T`` when max logT > ``min_logT_for_max_timestep_factor_at_high_T``.

      ! ::

    max_timestep_factor = 1.2d0
    max_timestep_factor_at_high_T = 1.1d0
    min_logT_for_max_timestep_factor_at_high_T = 1d99


      ! timestep_factor_for_retries
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Before retry, decrease dt by this.

      ! ::

    timestep_factor_for_retries = 0.5d0


      ! retry_hold
      ! ~~~~~~~~~~

      ! No increases in timestep for ``retry_hold`` steps after a retry.

      ! ::

    retry_hold = 1


      ! neg_mass_fraction_hold
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! No increases in timestep for ``neg_mass_fraction_hold`` steps after
      ! a retry caused by a negative mass fraction.

      ! ::

    neg_mass_fraction_hold = 2


      ! timestep_dt_factor
      ! ~~~~~~~~~~~~~~~~~~

      ! dt reduction factor exceed timestep limits.

      ! ::

    timestep_dt_factor = 0.9d0


      ! use_dt_low_pass_controller
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Enable low pass filter for smoother timestep variations.

      ! ::

    use_dt_low_pass_controller = .true.


      ! varcontrol_target
      ! ~~~~~~~~~~~~~~~~~

      ! This is the target value for relative variation in the structure from one model to the next.
      ! The default timestep adjustment is to increase or reduce the timestep depending on whether
      ! the actual variation was smaller or greater than this value.

      ! ::

    varcontrol_target = 1d-3


      ! min_allowed_varcontrol_target
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! The run will terminate if varcontrol_target < min_allowed_varcontrol_target
      ! It is not usually a good idea to reduce this.
      ! Instead, use time_delta_coeff to do time resolution convergence studies.

      ! ::

    min_allowed_varcontrol_target = 1d-4


      ! varcontrol_dt_limit_ratio_hard_max
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ``varcontrol_dt_limit_ratio`` is the actual varcontrol value divided by the target.
      ! if that ratio exceeds this limit, then retry with a smaller timestep.
      ! this let's you prevent large changes from happening in a single step.

      ! ::

    varcontrol_dt_limit_ratio_hard_max = 1d99


      ! never_skip_hard_limits
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! If true, then don't skip hard limits even immediately after a retry.

      ! ::

    never_skip_hard_limits = .true.


      ! relax_hard_limits_after_retry
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, then don't enforce hard limits immediately after a retry.

      ! ::

    relax_hard_limits_after_retry = .false.

      ! limits based on iterations required by various solvers


      ! solver_iters_timestep_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If solver solve uses more ``solver_iterations`` than this, reduce the next timestep.
      ! NOTE: when using gold tolerances, set gold_solver_iters_timestep_limit.

      ! ::

    solver_iters_timestep_limit = 7


      ! burn_steps_limit
      ! ~~~~~~~~~~~~~~~~

      ! If burn solver uses more steps than this, reduce the next timestep.

      ! ::

    burn_steps_limit = 10000


      ! burn_steps_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! If burn solver uses more steps than this, retry.

      ! ::

    burn_steps_hard_limit = 20000


      ! diffusion_steps_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! If diffusion solver uses more steps than this, reduce the next timestep.

      ! ::

    diffusion_steps_limit = 500


      ! diffusion_steps_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If diffusion solver uses more steps than this, retry.

      ! ::

    diffusion_steps_hard_limit = 700


      ! diffusion_iters_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! If use a total number of iters > this, reduce the next timestep.

      ! ::

    diffusion_iters_limit = 600


      ! diffusion_iters_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If use a total number of iters > this, retry.

      ! ::

    diffusion_iters_hard_limit = 800

      ! limits based on max decrease in mass fraction at any location in star


      ! dX_mix_dist_limit
      ! ~~~~~~~~~~~~~~~~~

      ! Option to ignore decreases in abundance in non-mixed cells near mixing boundaries.
      ! Ignore abundance changes if nearest mixing boundary is closer than this in Msun units.
      ! This applies to ``dX``, and ``dX_div_X`` limits.

      ! ::

    dX_mix_dist_limit = 1d-4

      ! dX_limit_species
      ! ~~~~~~~~~~~~~~~~

      ! Specify which species the ``dX_limit``, ``dX_div_X_limit``, etc array entries apply to.
      ! These are limits on magnitude of decrease in any cell abundance during a single timestep.
      ! dX here is ``abs(xa(j,k) - xa_old(j,k))`` for any cell k and all species j, eg ``'h1'``, ``'he4'``, etc.
      ! Special 'species' ``'X'`` (any hydrogen), ``'Y'`` (any helium) and ``'Z'`` (any metals) are
      ! allowed here. E.g. ``'Z'`` will trigger the timestep control if any metal isotope
      ! abundance individually satisfies the conditions below.
      ! Considers all cells except where have convective mixing.


      ! ::

    dX_limit_species(1) = 'h1'
    dX_limit_species(2) = 'he4'
    dX_limit_species(3:) = ''

      ! dX_limit_min_X
      ! ~~~~~~~~~~~~~~

      ! dX limits only apply where xa(j,k) >= this limit.

      ! ::

    dX_limit_min_X(:) = 1d99


      ! dX_limit
      ! ~~~~~~~~

      ! If max dX is greater than this,
      ! reduce the next timestep by ``dX_limit``/``max_dX``.

      ! ::

    dX_limit(:) = 1d99


      ! dX_hard_limit
      ! ~~~~~~~~~~~~~

      ! If max dX is greater than this, retry with smaller timestep.

      ! ::

    dX_hard_limit(:) = 1d99


      ! dX_decreases_only
      ! ~~~~~~~~~~~~~~~~~

      ! If true, then only consider decreases in abundance.
      ! ``dX_decreases_only`` applies to ``dX_div_X`` also.

      ! ::

    dX_decreases_only(:) = .true.

      ! Limit on magnitude of relative decrease in any cell abundance.
      ! ``dX_div_X`` here is abs(xa(j,k) - xa_old(j,k))/xa(j,k)
      ! for any cell k and any species j.
      ! Considers all cells except where have convective mixing.


      ! dX_div_X_limit_min_X
      ! ~~~~~~~~~~~~~~~~~~~~

      ! ``dX_div_X`` limits only apply where xa(j,k) >= this limit.

      ! ::

    dX_div_X_limit_min_X(1) = 1d-3
    dX_div_X_limit_min_X(2) = 1d-3
    dX_div_X_limit_min_X(3:) = 1d99


      ! dX_div_X_limit
      ! ~~~~~~~~~~~~~~

      ! If max ``dX_div_X`` is greater than this,
      ! reduce the next timestep by ``dX_limit/max_dX``.

      ! ::

    dX_div_X_limit(1) = 0.9d0
    dX_div_X_limit(2) = 0.9d0
    dX_div_X_limit(3:) = 1d99


      ! dX_div_X_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~

      ! If max ``dX_div_X`` is greater than this, retry with smaller timestep.

      ! ::

    dX_div_X_hard_limit(:) = 1d99


      ! dX_div_X_at_high_T_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! dX_div_X_at_high_T_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! dX_div_X_at_high_T_limit_lgT_min
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    dX_div_X_at_high_T_limit(:) = 1d99
    dX_div_X_at_high_T_hard_limit(:) = 1d99
    dX_div_X_at_high_T_limit_lgT_min(:) = 1d99

      ! Limits on max drop in abundance mass fraction from burning with possible mixing inflow.
      ! This considers both nuclear reactions and offsetting effect of mixing inflow.


      ! dX_nuc_drop_min_X_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! ``dX_nuc_drop_limit`` only for ``X > dX_nuc_drop_min_X_limit``.
      ! note that this is the abundance of the species, not the H1 abundance for the cell.
      ! i.e., if species abundance is below this limit, then ignore it for the dX_nuc_drop limit.

      ! ::

    dX_nuc_drop_min_X_limit = 1d-4


      ! dX_nuc_drop_max_A_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! ``dX_nuc_drop_limit`` only for species with ``A <= dX_nuc_drop_max_A_limit``.

      ! ::

    dX_nuc_drop_max_A_limit = 52


      ! dX_nuc_drop_limit_at_high_T
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Negative means use value for ``dX_nuc_drop_limit``,
      ! else use this limit when max logT > 9.45.

      ! ::

    dX_nuc_drop_limit_at_high_T = -1


      ! dX_nuc_drop_limit
      ! ~~~~~~~~~~~~~~~~~

      ! If max ``dX_nuc_drop`` is greater than ``dX_nuc_drop_limit``,
      ! reduce the next timestep by ``dX_nuc_drop_limit``/``max_dX_nuc_drop``.

      ! ::

    dX_nuc_drop_limit = 5d-2


      ! dX_nuc_drop_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! If max ``dX_nuc_drop`` is greater than ``dX_nuc_drop_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    dX_nuc_drop_hard_limit = 1d99


      ! dX_nuc_drop_min_yrs_for_dt
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Don't let ``dX_nuc_drop`` change dt to smaller than this.

      ! ::

    dX_nuc_drop_min_yrs_for_dt = 1d-9


   ! limits based on relative changes in variables L, P, Rho, T, R, eps_nuc
   ! ______________________________________________________________________

      ! limit on magnitude of relative change in L at any grid point

      ! ::

      !     dL_div_L = abs(L(k) - L_old(k))/L(k)


      ! dL_div_L_limit
      ! ~~~~~~~~~~~~~~

      ! If max abs ``dL_div_L`` is greater than this, reduce the next timestep.

      ! ::

    dL_div_L_limit = -1


      ! dL_div_L_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~

      ! If max abs ``dL_div_L`` is greater than this, retry with smaller timestep.

      ! ::

    dL_div_L_hard_limit = -1


      ! dL_div_L_limit_min_L
      ! ~~~~~~~~~~~~~~~~~~~~

      ! In Lsun units.
      ! ``dL_div_L`` limits only apply where ``L(k) >= Lsun*dL_limit_min_L``

      ! ::

    dL_div_L_limit_min_L = 1d99


      ! delta_lgP_limit
      ! ~~~~~~~~~~~~~~~

      ! Limit for magnitude of max change in log10 total pressure in any cell.

      ! ::

    delta_lgP_limit = 1


      ! delta_lgP_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If max ``delta_lgP`` is greater than ``delta_lgP_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lgP_hard_limit = -1


      ! delta_lgP_limit_min_lgP
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! ``delta_lgP_limit`` limits only apply where ``log10_P(k) >= delta_lgP_limit_min_lgP``

      ! ::

    delta_lgP_limit_min_lgP = 1d99


      ! delta_lgRho_limit
      ! ~~~~~~~~~~~~~~~~~

      ! Limit for magnitude of max change in log10 density in any cell.

      ! ::

    delta_lgRho_limit = 1


      ! delta_lgRho_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! If max ``delta_lgRho`` is greater than ``delta_lgRho_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lgRho_hard_limit = -1


      ! delta_lgRho_limit_min_lgRho
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ``delta_lgRho_limit`` limits only apply where ``log10_Rho(k) >= delta_lgRho_limit_min_lgRho``.

      ! ::

    delta_lgRho_limit_min_lgRho = 1d99


      ! delta_lgT_limit
      ! ~~~~~~~~~~~~~~~

      ! Limit for magnitude of max change in log10 temperature in any cell.

      ! ::

    delta_lgT_limit = 0.5d0


      ! delta_lgT_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If max ``delta_lgT`` is greater than ``delta_lgT_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lgT_hard_limit = -1


      ! delta_lgT_limit_min_lgT
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! ``delta_lgT_limit`` limits only apply where ``log10_T(k) >= delta_lgT_limit_min_lgT``.

      ! ::

    delta_lgT_limit_min_lgT = 1d99


      ! delta_lgE_limit
      ! ~~~~~~~~~~~~~~~

      ! Limit for magnitude of max change in log10 internal energy in any cell.

      ! ::

    delta_lgE_limit = 0.1d0


      ! delta_lgE_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If max ``delta_lgE`` is greater than ``delta_lgE_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lgE_hard_limit = -1


      ! delta_lgE_limit_min_lgE
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! ``delta_lgE_limit`` limits only apply where ``log10(E(k)) >= delta_lgE_limit_min_lgE``.

      ! ::

    delta_lgE_limit_min_lgE = 1d99


      ! delta_lgR_limit
      ! ~~~~~~~~~~~~~~~

      ! Limit for magnitude of max change in log10 radius at any cell boundary.

      ! ::

    delta_lgR_limit = 0.5d0


      ! delta_lgR_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If max ``delta_lgR`` is greater than ``delta_lgR_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lgR_hard_limit = -1


      ! delta_lgR_limit_min_lgR
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! ``delta_lgR_limit`` limits only apply where ``log10_R(k) >= delta_lgR_limit_min_lgR``.

      ! ::

    delta_lgR_limit_min_lgR = 1d99


      ! delta_Ye_highT_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Limit for magnitude of max change in Ye in high T cells.

      ! ::

    delta_Ye_highT_limit = 99

      ! Limit testing for max ``delta_ye`` to cells with ``T >= minT_for_highT_Ye_limit``
      ! If this high T max ``delta_Ye`` is greater than ``delta_Ye_highT_limit``,
      ! reduce the next timestep by ``delta_Ye_highT_limit``/``max_delta_Ye``.

      ! ::

      ! delta_Ye_highT_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

    delta_Ye_highT_hard_limit = -1


      ! minT_for_highT_Ye_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Limit testing for max ``delta_ye`` to cells with ``T >= minT_for_highT_Ye_limit``.
      ! If this high T max ``delta_Ye`` is greater than ``delta_Ye_highT_limit``,
      ! retry with smaller timestep.

      ! ::

    minT_for_highT_Ye_limit = 7d9


      ! delta_log_eps_nuc_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Limit for magnitude of max change in log10 ``eps_nuc`` in any cell.
      ! Only applies to increases in non-convective zones.

      ! ::

    delta_log_eps_nuc_limit = -1


      ! delta_log_eps_nuc_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max ``delta_log_eps_nuc`` is greater than ``delta_log_eps_nuc_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_log_eps_nuc_hard_limit = -1


   ! limits based on integrated power at each point for each category of nuclear reaction
   ! ____________________________________________________________________________________

      ! ``lgL_nuc_cat`` = nuclear reaction energy release for a particular category of reaction (Lsun units).
      ! Energy release here excludes neutrinos.


      ! delta_lgL_nuc_cat_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Limit for magnitude of change in ``lgL_nuc`` for category.

      ! ::

    delta_lgL_nuc_cat_limit = -1


      ! delta_lgL_nuc_cat_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lgL_nuc_cat_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lgL_nuc_cat_hard_limit = -1


      ! lgL_nuc_cat_burn_min
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lgL_nuc`` for category if value is less than this.

      ! ::

    lgL_nuc_cat_burn_min = -1


      ! lgL_nuc_mix_dist_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Ignore if nearest boundary is closer than this.
      ! Ignore changes in lgL in cells near mixing boundaries.

      ! ::

    lgL_nuc_mix_dist_limit = 1d-6

      ! ``L_H_burn`` = integrated power at surface from PP and CNO (in Lsun units)

      ! values for ``lgL_H`` are ``log10(max(1, L_H_burn))``


      ! delta_lgL_H_limit
      ! ~~~~~~~~~~~~~~~~~

      ! limit for magnitude of change in ``lgL_H``

      ! ::

    delta_lgL_H_limit = -1


      ! delta_lgL_H_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! if max delta is greater than ``delta_lgL_H_hard_limit``,
      ! retry with smaller timestep

      ! ::

    delta_lgL_H_hard_limit = -1


      ! lgL_H_burn_min
      ! ~~~~~~~~~~~~~~

      ! ignore changes in ``lgL_H`` if value is less than this

      ! ::

    lgL_H_burn_min = 1.5d0


      ! lgL_H_drop_factor
      ! ~~~~~~~~~~~~~~~~~

      ! when ``L_H`` is dropping, multiply limits by this factor

      ! ::

    lgL_H_drop_factor = 1


      ! lgL_H_burn_relative_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ignore changes in ``lgL_H`` if ``max(lgL_He,lgL_z) - lgL_H > this``

      ! ::

    lgL_H_burn_relative_limit = 3

      ! ``L_He_burn`` = integrated power at surface from triple alpha (in Lsun units)

      ! values for ``lgL_He`` are ``log10(max(1, L_He_burn))``


      ! delta_lgL_He_limit
      ! ~~~~~~~~~~~~~~~~~~

      ! Limit for magnitude of change in lgL_He.

      ! ::

    delta_lgL_He_limit = 0.025d0


      ! delta_lgL_He_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lgL_He_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lgL_He_hard_limit = -1


      ! lgL_He_burn_min
      ! ~~~~~~~~~~~~~~~

      ! Ignore changes in ``lgL_He`` if value is less than this.

      ! ::

    lgL_He_burn_min = 2.5d0


      ! lgL_He_drop_factor
      ! ~~~~~~~~~~~~~~~~~~

      ! When ``L_He`` is dropping, multiply limits by this factor.

      ! ::

    lgL_He_drop_factor = 1


      ! lgL_He_burn_relative_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lgL_He`` if ``max(lgL_H,lgL_z) - lgL_He > this``.

      ! ::

    lgL_He_burn_relative_limit = 3

      ! ``L_z_burn`` = integrated power at surface from nuclear burning other than H, He, or C (in Lsun units)
      ! excluding photodistintegrations

      ! values for ``lgL_z`` are ``log10(max(1, L_z_burn))``


      ! delta_lgL_z_limit
      ! ~~~~~~~~~~~~~~~~~

      ! Limit for magnitude of change in ``lgL_z``.

      ! ::

    delta_lgL_z_limit = -1


      ! delta_lgL_z_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lgL_z_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lgL_z_hard_limit = -1


      ! lgL_z_burn_min
      ! ~~~~~~~~~~~~~~

      ! Ignore changes in ``lgL_z`` if value is less than this.

      ! ::

    lgL_z_burn_min = 2.5d0


      ! lgL_z_drop_factor
      ! ~~~~~~~~~~~~~~~~~

      ! When ``L_z`` is dropping, multiply limits by this factor.

      ! ::

    lgL_z_drop_factor = 1


      ! lgL_z_burn_relative_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lgL_z`` if ``max(lgL_H,lgL_He) - lgL_z > this``.

      ! ::

    lgL_z_burn_relative_limit = 3


   ! limits based on total integrated power at surface for all nuclear reactions
   ! ___________________________________________________________________________

      ! excluding photodistintegrations

      ! ``L_nuc`` = nuclear reaction total energy release for all nuclear reactions (Lsun units)


      ! delta_lgL_nuc_limit
      ! ~~~~~~~~~~~~~~~~~~~
      ! delta_lgL_nuc_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lgL_nuc_at_high_T_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lgL_nuc_at_high_T_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lgL_nuc_at_high_T_limit_lgT_min
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_lgT_for_lgL_nuc_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! When ``L_nuc`` is dropping, multiply limits by ``lgL_nuc_drop_factor``.

      ! ignore changes in ``lgL_nuc`` if max logT > ``max_lgT_for_lgL_nuc_limit``.

      ! limit for magnitude of change in ``lgL_nuc``
      ! retry if max delta is greater than ``delta_lgL_nuc_hard_limit``,
      ! ignore changes in ``lgL_nuc`` if value is less than ``lgL_nuc_burn_min``

      ! if max logT is > ``delta_lgL_nuc_at_high_T_limit_lgT_min`` then
      !    use ``delta_lgL_nuc_at_high_T_limit`` and ``delta_lgL_nuc_at_high_T_hard_limit``
      ! else
      !    use ``delta_lgL_nuc_limit`` and ``delta_lgL_nuc_hard_limit``

      ! at extreme temperatures, can have numerical jitters in this
      ! as a result of almost cancelling large positive and negative
      ! contributions of forward and reverse rates such as
      ! photodisintegration and rebuilding of he4
      ! so if doing advanced burning, may want to turn off lgL_nuc limits above some max logT
      ! and turn on lgL_power_photo limits at a somewhat smaller max logT.

      ! ::

    delta_lgL_nuc_limit = -1
    delta_lgL_nuc_hard_limit = -1

      ! ::

    delta_lgL_nuc_at_high_T_limit = -1
    delta_lgL_nuc_at_high_T_hard_limit = -1
    delta_lgL_nuc_at_high_T_limit_lgT_min = 1d99

      ! ::

    max_lgT_for_lgL_nuc_limit = 1d99
    lgL_nuc_burn_min = 0.5d0
    lgL_nuc_drop_factor = 10


   ! limits based on total integrated power at surface for photodistintegrations
   ! ___________________________________________________________________________

      ! ``L_photo`` = nuclear reaction total energy release for all photodistintegrations (Lsun units)
      ! note that photodistintegrations consume energy so the total released is negative.
      ! photodisintegrations become large during late burning at high temperatures.
      ! values for ``lgL_photo`` are based on ``L_by_category(iphoto)``


      ! delta_lgL_power_photo_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lgL_power_photo_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_lgT_for_lgL_power_photo_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! lgL_power_photo_burn_min
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! lgL_power_photo_drop_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Limit for magnitude of change in ``lgL_photo``.
      ! If max delta is greater than ``delta_lgL_power_photo_hard_limit``,
      ! retry with smaller timestep.
      ! ignore delta_lgL_power_photo_limit when max logT < ``min_lgT_for_lgL_power_photo_limit``.
      ! Ignore changes in ``lgL_photo`` if value is less than ``lgL_power_photo_burn_min``.
      ! When ``L_photo`` is dropping, multiply limits by ``lgL_power_photo_drop_factor``.

      ! ::

    delta_lgL_power_photo_limit = -1
    delta_lgL_power_photo_hard_limit = -1
    min_lgT_for_lgL_power_photo_limit = 9d0
    lgL_power_photo_burn_min = 10d0
    lgL_power_photo_drop_factor = 10


      ! limits based on changes at photosphere


      ! delta_lgTeff_limit
      ! ~~~~~~~~~~~~~~~~~~
      ! delta_lgTeff_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Limit for magnitude of max change in log10 temperature at photosphere.

      ! ::

    delta_lgTeff_limit = 0.01d0
    delta_lgTeff_hard_limit = -1


      ! delta_lgL_limit_L_min
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! delta_lgL_limit
      ! ~~~~~~~~~~~~~~~
      ! delta_lgL_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Limit for magnitude of change in log10(L_surf/Lsun).
      ! Only apply this limit when ``L_surf`` >= ``delta_lgL_limit_L_min`` (in Lsun units).

      ! ::

    delta_lgL_limit_L_min = -100
    delta_lgL_limit = 0.1d0
    delta_lgL_hard_limit = -1


      ! dt_div_min_dr_div_cs_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! dt_div_min_dr_div_cs_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! limit for dt compared to explicit solver timescale (negative means no limit)

      ! ::

      !     min_dr_div_cs = min over all cells of dr/csound (seconds)

      ! ::

    dt_div_min_dr_div_cs_limit = -1
    dt_div_min_dr_div_cs_hard_limit = -1


      ! dt_div_dt_cell_collapse_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! dt_div_dt_cell_collapse_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! limit for dt compared to cell_collapse timescale (negative means no limit)

      ! ::

      !     dt_cell_collapse = min over shells k that have v(k+1) > v(k) of
      !     (r(k)-r(k+1))/(v(k+1)-v(k)), the time for the cell to collapse
      !     to zero thickness at current velocities.  only for v_flag true.

      ! ::

    dt_div_dt_cell_collapse_limit = -1
    dt_div_dt_cell_collapse_hard_limit = -1


      ! min_k_for_dt_div_min_dr_div_cs_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_q_for_dt_div_min_dr_div_cs_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_q_for_dt_div_min_dr_div_cs_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! check_remnant_only_for_dt_div_min_dr_div_cs_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    min_k_for_dt_div_min_dr_div_cs_limit = 20
    min_q_for_dt_div_min_dr_div_cs_limit = 0.005d0
    max_q_for_dt_div_min_dr_div_cs_limit = 0.995d0
    check_remnant_only_for_dt_div_min_dr_div_cs_limit = .false.


      ! min_abs_u_div_cs_for_dt_div_min_dr_div_cs_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! min_abs_du_div_cs_for_dt_div_min_dr_div_cs_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! only use ``dt_div_min_dr_div_cs_limit`` at cells where
      ! ``abs_du_div_cs`` > ``min_abs_du_div_cs_for_dt_div_min_dr_div_cs_limit`` and
      ! and
      ! ``abs_u_div_cs`` > ``min_abs_u_div_cs_for_dt_div_min_dr_div_cs_limit``
      !
      ! allow focus on regions near shock face.

      ! ::

    min_abs_u_div_cs_for_dt_div_min_dr_div_cs_limit = 0.8d0
    min_abs_du_div_cs_for_dt_div_min_dr_div_cs_limit = 0.01d0

      ! limits based on changes in location on HR diagram


      ! delta_HR_ds_L
      ! ~~~~~~~~~~~~~
      ! delta_HR_ds_Teff
      ! ~~~~~~~~~~~~~~~~

      ! ::

      !     dlgL = log10(L/L_prev)
      !     dlgTeff = log10(Teff/Teff_prev)

      ! ::

    delta_HR_ds_L = 1
    delta_HR_ds_Teff = 1


      ! delta_HR_limit
      ! ~~~~~~~~~~~~~~
      ! delta_HR_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~

      ! limit for dHR (negative means no limit)

      ! ::

      !     dHR = sqrt((delta_HR_ds_L*dlgL)**2 + (delta_HR_ds_Teff*dlgTeff)**2)

      ! ::

    delta_HR_limit = -1
    delta_HR_hard_limit = -1


      ! delta_lgT_max_limit
      ! ~~~~~~~~~~~~~~~~~~~
      ! delta_lgT_max_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lgT_max_limit_lgT_min
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lgT_max_at_high_T_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lgT_max_at_high_T_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lgT_max_at_high_T_limit_lgT_min
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lgT_max_limit_only_after_near_zams
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! limit for magnitude of change in max over all cells of log10 T
      ! this is for off center flashes in degenerate material (e.g., He or Ne)
      ! Only apply this limit when ``lgT_max`` >= ``delta_lgT_max_limit_lgT_min``.

      ! similarly, use ``at_high_T`` limits only
      ! when ``lgT_max`` >= ``delta_lgT_max_at_high_T_limit_lgT_min``.
      ! this can be useful since higher order temperature sensitivity of rates at high T
      ! may require smaller limits for changes.

      ! ::

    delta_lgT_max_limit = -1
    delta_lgT_max_hard_limit = -1
    delta_lgT_max_limit_lgT_min = 9d0

      ! ::

    delta_lgT_max_at_high_T_limit = -1
    delta_lgT_max_at_high_T_hard_limit = -1
    delta_lgT_max_at_high_T_limit_lgT_min = -1

      ! ::

    delta_lgT_max_limit_only_after_near_zams = .false.

      ! limits based on changes at center


      ! delta_lgT_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~
      ! delta_lgT_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lgT_cntr_limit_only_after_near_zams
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! limit for magnitude of change in log10 temperature at center

      ! ::

    delta_lgT_cntr_limit = 0.01d0
    delta_lgT_cntr_hard_limit = -1
    delta_lgT_cntr_limit_only_after_near_zams = .true.


      ! delta_lgP_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~
      ! delta_lgP_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! limit for magnitude of change in log10 pressure at center

      ! ::

    delta_lgP_cntr_limit = -1
    delta_lgP_cntr_hard_limit = -1


      ! delta_lgRho_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lgRho_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! limit for magnitude of change in log10 density at center

      ! ::

    delta_lgRho_cntr_limit = 0.05d0
    delta_lgRho_cntr_hard_limit = -1

      ! ``dX_div_X_cntr`` is max(abs(xa(j,nz)-xa_old(j,nz))/xa(j,nz)) for any species j
      ! Small timesteps as the center carbon is exhausted.


      ! delta_dX_div_X_cntr_min
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``dX_div_X_cntr`` if value is less than this.

      ! ::

    delta_dX_div_X_cntr_min = -5


      ! delta_dX_div_X_cntr_max
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``dX_div_X_cntr`` if value is more than this.

      ! ::

    delta_dX_div_X_cntr_max = 0


      ! delta_dX_div_X_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_dX_div_X_cntr_limit``,
      ! reduce the next timestep by ``delta_dX_div_X_cntr_limit``/``max_delta``.

      ! ::

    delta_dX_div_X_cntr_limit = 0.1d0


      ! delta_dX_div_X_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_dX_div_X_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_dX_div_X_cntr_hard_limit = -1

      ! ``lg_XH_cntr`` is log10(h1 mass fraction at center).
      ! Small timesteps as the center hydrogen is exhausted.


      ! delta_lg_XH_cntr_min
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lg_XH_cntr`` if value is less than this.

      ! ::

    delta_lg_XH_cntr_min = -6


      ! delta_lg_XH_cntr_max
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lg_XH_cntr`` if value is more than this.

      ! ::

    delta_lg_XH_cntr_max = 0


      ! delta_lg_XH_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than this,
      ! reduce the next timestep by ``delta_lg_XH_cntr_limit``/``max_delta``.

      ! ::

    delta_lg_XH_cntr_limit = 0.05d0


      ! delta_lg_XH_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lg_XH_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lg_XH_cntr_hard_limit = -1

      ! ``lg_XHe_cntr`` is log10(he4 mass fraction at center)
      ! small timesteps as the center helium is exhausted.


      ! delta_lg_XHe_cntr_min
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lg_XHe_cntr`` if value is less than this.

      ! ::

    delta_lg_XHe_cntr_min = -6


      ! delta_lg_XHe_cntr_max
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lg_XHe_cntr`` if value is more than this.

      ! ::

    delta_lg_XHe_cntr_max = 0


      ! delta_lg_XHe_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lg_XHe_cntr_limit``,
      ! reduce the next timestep by ``delta_lg_XHe_cntr_limit``/``max_delta``.

      ! ::

    delta_lg_XHe_cntr_limit = 0.1d0


      ! delta_lg_XHe_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lg_XHe_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lg_XHe_cntr_hard_limit = -1

      ! ``lg_XC_cntr`` is log10(c12 mass fraction at center).
      ! Small timesteps as the center carbon is exhausted.


      ! delta_lg_XC_cntr_min
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lg_XC_cntr`` if value is less than this.

      ! ::

    delta_lg_XC_cntr_min = -5


      ! delta_lg_XC_cntr_max
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lg_XC_cntr`` if value is more than this.

      ! ::

    delta_lg_XC_cntr_max = 0


      ! delta_lg_XC_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lg_XC_cntr_limit``,
      ! reduce the next timestep by ``delta_lg_XC_cntr_limit``/``max_delta``.

      ! ::

    delta_lg_XC_cntr_limit = 0.1d0


      ! delta_lg_XC_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lg_XC_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lg_XC_cntr_hard_limit = -1

      ! ``lg_XO_cntr`` is log10(o16 mass fraction at center)
      ! Small timesteps as the center oxygen is exhausted.


      ! delta_lg_XNe_cntr_min
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lg_XNe_cntr`` if value is less than this.

      ! ::

    delta_lg_XNe_cntr_min = -5


      ! delta_lg_XNe_cntr_max
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lg_XNe_cntr`` if value is more than this.

      ! ::

    delta_lg_XNe_cntr_max = 0


      ! delta_lg_XNe_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lg_XNe_cntr_limit``,
      ! reduce the next timestep by ``delta_lg_XNe_cntr_limit``/``max_delta``.

      ! ::

    delta_lg_XNe_cntr_limit = 1d99


      ! delta_lg_XNe_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lg_XNe_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lg_XNe_cntr_hard_limit = -1


      ! delta_lg_XO_cntr_min
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lg_XO_cntr`` if value is less than this.

      ! ::

    delta_lg_XO_cntr_min = -5


      ! delta_lg_XO_cntr_max
      ! ~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lg_XO_cntr`` if value is more than this.

      ! ::

    delta_lg_XO_cntr_max = 0


      ! delta_lg_XO_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lg_XO_cntr_limit``,
      ! reduce the next timestep by ``delta_lg_XO_cntr_limit``/``max_delta``.

      ! ::

    delta_lg_XO_cntr_limit = 1d99


      ! delta_lg_XO_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lg_XO_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lg_XO_cntr_hard_limit = -1

      ! delta_lg_XSi_cntr_min
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lg_XSi_cntr`` if value is less than this.

      ! ::

    delta_lg_XSi_cntr_min = -5


      ! delta_lg_XSi_cntr_max
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! Ignore changes in ``lg_XSi_cntr`` if value is more than this.

      ! ::

    delta_lg_XSi_cntr_max = 0


      ! delta_lg_XSi_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lg_XSi_cntr_limit``,
      ! reduce the next timestep by ``delta_lg_XSi_cntr_limit``/``max_delta``.

      ! ::

    delta_lg_XSi_cntr_limit = 1d99


      ! delta_lg_XSi_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_lg_XSi_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_lg_XSi_cntr_hard_limit = -1


      ! delta_XH_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than this,
      ! reduce the next timestep by ``delta_XH_cntr_limit``/``max_delta``.

      ! ::

    delta_XH_cntr_limit = 0.01d0


      ! delta_XH_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_XH_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_XH_cntr_hard_limit = -1


      ! delta_XHe_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_XHe_cntr_limit``,
      ! reduce the next timestep by ``delta_XHe_cntr_limit``/``max_delta``.

      ! ::

    delta_XHe_cntr_limit = 0.01d0


      ! delta_XHe_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_XHe_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_XHe_cntr_hard_limit = -1


      ! delta_XC_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_XC_cntr_limit``,
      ! reduce the next timestep by ``delta_XC_cntr_limit``/``max_delta``.

      ! ::

    delta_XC_cntr_limit = 0.01d0


      ! delta_XC_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_XC_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_XC_cntr_hard_limit = -1


      ! delta_XNe_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_XNe_cntr_limit``,
      ! reduce the next timestep by ``delta_XNe_cntr_limit``/``max_delta``.

      ! ::

    delta_XNe_cntr_limit = 0.01d0


      ! delta_XNe_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_XNe_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_XNe_cntr_hard_limit = -1


      ! delta_XO_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_XO_cntr_limit``,
      ! reduce the next timestep by ``delta_XO_cntr_limit``/``max_delta``.

      ! ::

    delta_XO_cntr_limit = 0.01d0


      ! delta_XO_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_XO_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_XO_cntr_hard_limit = -1


      ! delta_XSi_cntr_limit
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_XSi_cntr_limit``,
      ! reduce the next timestep by ``delta_XSi_cntr_limit``/``max_delta``.

      ! ::

    delta_XSi_cntr_limit = 0.01d0


      ! delta_XSi_cntr_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If max delta is greater than ``delta_XSi_cntr_hard_limit``,
      ! retry with smaller timestep.

      ! ::

    delta_XSi_cntr_hard_limit = -1


      ! delta_dX_div_X_drop_only
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lg_XH_drop_only
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! delta_lg_XHe_drop_only
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lg_XC_drop_only
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! delta_lg_XNe_drop_only
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lg_XO_drop_only
      ! ~~~~~~~~~~~~~~~~~~~~~
      ! delta_lg_XSi_drop_only
      ! ~~~~~~~~~~~~~~~~~~~~~~
      ! delta_XH_drop_only
      ! ~~~~~~~~~~~~~~~~~~
      ! delta_XHe_drop_only
      ! ~~~~~~~~~~~~~~~~~~~
      ! delta_XC_drop_only
      ! ~~~~~~~~~~~~~~~~~~
      ! delta_XNe_drop_only
      ! ~~~~~~~~~~~~~~~~~~~
      ! delta_XO_drop_only
      ! ~~~~~~~~~~~~~~~~~~
      ! delta_XSi_drop_only
      ! ~~~~~~~~~~~~~~~~~~~


      ! If true, then only limit drops in abundance.

      ! ::

   delta_dX_div_X_drop_only = .false.
   delta_lg_XH_drop_only = .false.
   delta_lg_XHe_drop_only = .false.
   delta_lg_XC_drop_only = .false.
   delta_lg_XNe_drop_only = .false.
   delta_lg_XO_drop_only = .false.
   delta_lg_XSi_drop_only = .false.
   delta_XH_drop_only = .false.
   delta_XHe_drop_only = .false.
   delta_XC_drop_only = .false.
   delta_XNe_drop_only = .false.
   delta_XO_drop_only = .false.
   delta_XSi_drop_only = .false.


   ! limits based on changes in mass of the star
   ! ___________________________________________


      ! delta_lg_star_mass_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! delta_lg_star_mass_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Limit for magnitude of change in log10(M/Msun).

      ! ::

    delta_lg_star_mass_limit = 5d-3
    delta_lg_star_mass_hard_limit = -1

      ! delta_mdot_atol
      ! ~~~~~~~~~~~~~~~
      ! delta_mdot_rtol
      ! ~~~~~~~~~~~~~~~

      ! limit for change in mdot in Msun/yr
      ! + ``delta_mdot_atol`` tolerance for absolute changes
      ! + ``delta_mdot_rtol`` tolerance for relative changes

      ! ::

    delta_mdot_atol = 1d-3
    delta_mdot_rtol = 0.5d0


      ! delta_mdot_limit
      ! ~~~~~~~~~~~~~~~~
      ! delta_mdot_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! ::

      !     delta_mot = abs(mdot - mdot_old)/ (delta_mdot_atol*Msun/secyer + &
      !        delta_mdot_rtol*max(abs(mdot),abs(mdot_old)))

      ! ignore if < 0

      ! ::

    delta_mdot_limit = -1
    delta_mdot_hard_limit = -1


      ! adjust_J_q_limit
      ! ~~~~~~~~~~~~~~~~
      ! adjust_J_q_hard_limit
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! limit for mass coordinate down to which angular momentum is adjusted when
      ! using do_adjust_J_lost

      ! ::

    adjust_J_q_limit = 0.99
    adjust_J_q_hard_limit = 0.98


      ! limit_for_rel_error_in_energy_conservation
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! hard_limit_for_rel_error_in_energy_conservation
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

      !     rel_error_in_energy_conservation = abs(error_in_energy_conservation/total_energy)

      ! ::

    limit_for_rel_error_in_energy_conservation = 1d-4
    hard_limit_for_rel_error_in_energy_conservation = 1d-3


      ! report_min_dr_div_cs
      ! ~~~~~~~~~~~~~~~~~~~~

      ! If true, produce terminal output about minimum of cell dr/cs

      ! ::

    report_min_dr_div_cs = .false.


      ! report_dt_hard_limit_retries
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, produce terminal output about choice of timestep.

      ! ::

    report_dt_hard_limit_retries = .false.


      ! report_solver_dt_info
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! If true, produce terminal output about choice of timestep based on ``varcontrol_target``.

      ! ::

    report_solver_dt_info = .false.

! debugging controls
! ==================


      ! report_solver_progress
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! Set true to see info about solver iterations.

      ! ::

    report_solver_progress = .false.


      ! report_ierr
      ! ~~~~~~~~~~~

      ! If true, produce terminal output when have some internal error.

      ! ::

    report_ierr = .false.


      ! report_bad_negative_xa
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! If true, produce terminal output when have bad negative mass fraction error.

      ! ::

    report_bad_negative_xa = .false.


      ! stop_for_bad_nums
      ! ~~~~~~~~~~~~~~~~~

      ! If true, then stop for bad numbers (NaNs or infinity).
      ! this replaces old control stop_for_NaNs

      ! ::

    stop_for_bad_nums = .false.


      ! show_mesh_changes
      ! ~~~~~~~~~~~~~~~~~

      ! When ``show_mesh_changes`` is true, the terminal output includes the ``mesh_call_number``.

      ! ::

    show_mesh_changes = .false.


      ! trace_evolve
      ! ~~~~~~~~~~~~

      ! Send evolve output to screen.

      ! ::

    trace_evolve = .false.

      ! variety of output from the solver

      ! ::

    solver_numerical_jacobian = .false.
    solver_jacobian_nzlo = 1
    solver_jacobian_nzhi = -1
    solver_check_everything = .false.
    solver_inspect_soln_flag = .false.
    solver_test_partials_dx_0 = -1d0
    solver_test_partials_k = -1
    solver_test_partials_k_low = -1
    solver_test_partials_k_high = -1
    solver_test_eos_partials = .false.
    solver_test_kap_partials = .false.
    solver_test_net_partials = .false.
    solver_test_atm_partials = .false.
    solver_test_partials_var_name = ''
    solver_test_partials_sink_name = ''
    solver_test_partials_equ_name = ''
    solver_test_partials_show_dx_var_name = ''
    solver_show_correction_info = .false.
    solver_test_partials_call_number = -1
    solver_test_partials_iter_number = -1
    solver_test_partials_write_eos_call_info = .false.
    solver_epsder_struct = 1d-5
    solver_epsder_chem = 1d-5

    energy_conservation_dump_model_number = -1


      ! solver_save_photo_call_number
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! Saves a photo when solver_call_number = solver_save_photo_call_number - 1

      ! ::

    solver_save_photo_call_number = -1


      ! xa_clip_limit
      ! ~~~~~~~~~~~~~

      ! Abundances smaller than this limit are set to 0.

      ! ::

    xa_clip_limit = 1d-99


      ! fill_arrays_with_NaNs
      ! ~~~~~~~~~~~~~~~~~~~~~

      ! initialize arrays with NaNs to trap reads of uninitialized entries.

      ! ::

    fill_arrays_with_NaNs = .false.


      ! zero_when_allocate
      ! ~~~~~~~~~~~~~~~~~~

      ! initialize arrays with zeros.

      ! ::

    zero_when_allocate = .false.

! miscellaneous controls
! ======================


      ! warn_rates_for_high_temp
      ! ~~~~~~~~~~~~~~~~~~~~~~~~
      ! max_safe_logT_for_rates
      ! ~~~~~~~~~~~~~~~~~~~~~~~~

      ! If true, then when any zone tries to evaluate a rate above ``max_safe_logT_for_rates``
      ! it generates a warning message. The code will cap the rate at the value
      ! for ``max_safe_logT_for_rates`` whether the warning is on or not.
      ! 10d0 is a sensible default for the max temperature, as that is where the partition tables
      ! and polynomial fits to the rates are valid until.
      ! warning messages include the text "rates have been truncated" and "WARNING: evaluating rates".

      ! ::

    warn_rates_for_high_temp = .true.
    max_safe_logT_for_rates = 10d0


      ! warn_when_large_rel_run_E_err
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! message includes the text "WARNING: rel_run_E_err"

      ! rel_run_E_err = abs(cumulative_energy_error/total_energy)
      ! you can turn off this warning message by setting this to a large number.

      ! ::

    warn_when_large_rel_run_E_err = 0.1d0

      ! absolute_cumulative_energy_err
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! cumulative energy error is the sum of the absolute value of per-step errors.
      ! Set this to .false. to allow positive and negative errors to cancel
      ! when integrating over multiple steps.

      ! ::

    absolute_cumulative_energy_err = .true.


      ! warning_limit_for_max_residual
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! message includes the text "WARNING: max_residual > warning_limit_for_max_residual"

      ! ::

    warning_limit_for_max_residual = 1d0


      ! warn_when_large_virial_thm_rel_err
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! message includes the text "WARNING: virial_thm_rel_err"
      ! only applies to models with no velocities, rotation, or mass change.

      ! ::

    warn_when_large_virial_thm_rel_err = 1d-2


      ! warn_when_get_a_bad_eos_result
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! message includes the text "WARNING eos:"

      ! ::

    warn_when_get_a_bad_eos_result = .true.


      ! relax_dY
      ! ~~~~~~~~

      ! Change Y by this amount per step when relaxing Y.

      ! ::

    relax_dY = 0.005d0


      ! relax_dlnZ
      ! ~~~~~~~~~~

      ! Change lnZ by this amount per step when relaxing Z.
      ! Default is ln10/10.

      ! ::

    relax_dlnZ = 2.3025850929940459d-1


      ! eps_mdot_leak_frac_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~

      ! ::

    eps_mdot_leak_frac_factor = 1d0


      ! zams_filename
      ! ~~~~~~~~~~~~~

      ! Default is for Z=0.02, Y=0.28.

      ! ::

    zams_filename = 'zams_z2m2_y28.data'

      ! set_rho_to_dm_div_dV
      ! ~~~~~~~~~~~~~~~~~~~~

      ! ::

    set_rho_to_dm_div_dV = .true.


      ! steps_before_start_stress_test
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! stress_test_relax
      ! ~~~~~~~~~~~~~~~~~

      ! ::

    steps_before_start_stress_test = 0
    stress_test_relax = .false.


      ! use_other_{hook}
      ! ~~~~~~~~~~~~~~~~

      ! Logicals to deploy the use_other routines.

      ! ::

    use_other_kap = .false.
    use_other_diffusion = .false.
    use_other_mlt_results = .false.

      ! ::

    use_other_adjust_mdot = .false.
    use_other_j_for_adjust_J_lost = .false.
    use_other_alpha_mlt = .false.
    use_other_am_mixing = .false.
    use_other_brunt = .false.
    use_other_brunt_smoothing = .false.
    use_other_build_initial_model = .false.
    use_other_cgrav = .false.
    use_other_mesh_delta_coeff_factor = .false.

      ! ::

    use_other_energy_implicit = .false.
    use_other_energy = .false.
    use_other_pressure = .false.
    use_other_momentum_implicit = .false.
    use_other_momentum = .false.
    use_other_eps_grav = .false.
    use_other_mesh_functions = .false.
    use_other_D_mix = .false.
    use_other_close_gaps = .false.

      ! ::

    use_other_neu = .false.
    use_other_net_get = .false.
    use_other_solver_monitor = .false.
    use_other_opacity_factor = .false.
    use_other_diffusion_factor = .false.
    use_other_diffusion_coefficients = .false.
    use_other_pgstar_plots = .false.
    use_other_gradr_factor = .false.
    use_other_eval_fp_ft = .false.
    use_other_torque = .false.
    use_other_screening = .false.
    use_other_rate_get = .false.
    use_other_net_derivs = .false.
    use_other_split_burn = .false.

      ! ::

    use_other_torque_implicit = .false.
    use_other_wind = .false.
    use_other_after_struct_burn_mix = .false.
    use_other_before_struct_burn_mix = .false.
    use_other_surface_PT = .false.
    use_other_remove_surface = .false.
    use_other_set_pgstar_controls = .false.
    use_other_accreting_state = .false.
    use_other_eval_i_rot = .false.

      ! ::

    use_other_export_pulse_data = .false.
    use_other_get_pulse_data = .false.
    use_other_edit_pulse_data = .false.

      ! ::

    use_other_astero_freq_corr = .false.

      ! ::

    use_other_timestep_limit = .false.


   ! mixing diffusion coeffs
   ! _______________________


      ! sig_term_limit
      ! ~~~~~~~~~~~~~~

      ! Limit on coefficients in convective mixing equations.
      ! Consider a diffusion eqn of form:

      ! ::

      !     x(k) - x0(k) = c1*(x(k-1) - x(k)) - c2*(x(k) - x(k+1))

      ! Simplify for c1=c2=c, x(k-1)=x(k+1)=x0(k)=x0, x(k)=x0+dx
      ! Then eqn becomes

      ! ::

      !     (1+2*c)*(x0+dx) - 2*c*x0 = x0

      ! If ``2*c >> 1``, then eqn becomes ill-conditioned,
      ! so we enforce ``c <= sig_term_limit``
      ! In physical terms c is ``dt*sig/dm``, where
      ! ``sig = (4 pi r^2 rho)^2*D`` and D = diffusion coeff (cm^2/s),
      ! so c can get large when dt/dm is large.

      ! ::

    sig_term_limit = 1d13


      ! am_sig_term_limit
      ! ~~~~~~~~~~~~~~~~~

      ! Limit on coefficients in angular momentum transport equations.
      ! Necessary for numerical stability.
      ! Plays same role as ``sig_term_limit`` for material mixing.

      ! ::

    am_sig_term_limit = 1d13


      ! sig_min_factor_for_high_Tcenter
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! High center T limit to avoid negative mass fractions.
      ! If Tcenter >= ``Tcenter_min_for_sig_min_factor_full_on``,
      ! then okay to reduce sig by as much as this factor
      ! as needed to prevent causing negative abundances.
      ! Inactive when >= 1d0.

      ! ::

    sig_min_factor_for_high_Tcenter = 0.01d0


      ! Tcenter_min_for_sig_min_factor_full_on
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If Tcenter >= this, factor = ``sig_min_factor_for_neg_abundances``,
      ! this should be > ``Tcenter_max_for_sig_min_factor_full_off``.

      ! ::

    Tcenter_min_for_sig_min_factor_full_on = 3.2d9


      ! Tcenter_max_for_sig_min_factor_full_off
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If Tcenter <= this, factor = 1, so has no effect
      ! this should be < ``Tcenter_min_for_sig_min_factor_full_on``.
      ! For T > ``full_off`` and < ``full_on``, factor changes linearly with Tcenter.

      ! ::

    Tcenter_max_for_sig_min_factor_full_off = 2.8d9


      ! max_delta_m_to_bdy_for_sig_min_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! sig_min factor goes to 1 as distance (in Msun units)
      ! from boundary of mixing region reaches this value

      ! ::

    max_delta_m_to_bdy_for_sig_min_factor = 0.5d0


      ! delta_m_upper_for_sig_min_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! okay to change sig min factor to 1 for mix region larger than this

      ! ::

    delta_m_upper_for_sig_min_factor = 0.3d0


      ! delta_m_lower_for_sig_min_factor
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! don't change sig min factor for mix region smaller than this

      ! ::

    delta_m_lower_for_sig_min_factor = 0.1d0


      ! x_ctrl
      ! ~~~~~~

      ! extra params as a convenience for developing new features.
      ! use ``x_ctrl`` for floats, ``x_integer_ctrl`` for integers, ``x_logical_ctrl`` for booleans,
      ! and ``x_character_ctrl`` for strings.
      ! note: the parameter ``num_x_ctrls`` is defined in ``star_def.inc``

      ! ::

    x_ctrl(1:num_x_ctrls) = 0d0
    x_integer_ctrl(1:num_x_ctrls) = 0
    x_logical_ctrl(1:num_x_ctrls) = .false.
    x_character_ctrl(1:num_x_ctrls) = ''

      ! One can split controls inlist into pieces using the following parameters.
      ! BTW: it works recursively, so the extras can read extras too.


      ! read_extra_controls_inlist(1..5)
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ! extra_controls_inlist_name(1..5)
      ! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      ! If ``read_extra_controls_inlist(1)`` is true, then read &controls from this namelist file.

      ! ::

    read_extra_controls_inlist(:) = .false.
    extra_controls_inlist_name(:) = 'undefined'

      ! save_controls_namelist
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! dumps all values for &controls namelist to file

      ! ::

    save_controls_namelist = .false.


      ! controls_namelist_name
      ! ~~~~~~~~~~~~~~~~~~~~~~

      ! if empty, uses a default name

      ! ::

    controls_namelist_name = ''