[Mesa-users] Load saved model vs create PMS model

[Roque Caballero]

Dear all,

I'm trying to reproduce the MESA 2019 exercise (link 
<http://doi.org/10.5281/zenodo.3374959>) proposed by Professor Marc 
Pinsonneault and I'm getting some problems for which I'm not able to 
understand the reason.

The inlist of that exercise used a a pre-computed PMS model. If a run 
the simulation with the unmodified inlist file, it works. On the other 
hand, if I configure the inlist for not using the pre-computed model but 
for generating it,

/    create_pre_main_sequence_model = .true./
/    load_saved_model = .false./

I get the following error after a few seconds when I run the simulation:


    /  -2.0889505372223345E-012  -2.0395779779221372E-012
    -1.9901408914903830E-012  -1.9405185782435689E-012//
    // retry       1//
    //                           1st model retry log10(dt/yr)
    -5.3010299956639804D+00//
    // retry       1//
    //                           1st model retry log10(dt/yr)
    -5.6020599913279616D+00//
    //backup       1//
    //                           1st model retry log10(dt/yr)
    -7.6020599913279616D+00//
    // retry       1//
    //                           1st model retry log10(dt/yr)
    -7.9030899869919429D+00//
    // retry       1//
    //                           1st model retry log10(dt/yr)
    -8.2041199826559232D+00//
    //backup       1//
    //                           1st model retry log10(dt/yr)
    -1.0806179973983886D+01//
    // retry       1//
    //                           1st model retry log10(dt/yr)
    -1.1107209969647867D+01//
    // retry       1//
    //                           1st model retry log10(dt/yr)
    -1.1408239965311848D+01//
    //dt    7.7046264609375016D-08//
    //min_timestep_limit    9.9999999999999995D-07//
    //
    // stopping because of problems dt < min_timestep_limit//
    //
    //
    //terminated evolution: cannot find acceptable model//
    //
    //termination code: min_timestep_limit//
    //DATE: 2020-06-09//
    //TIME: 20:31:14//
    /

Could any one help me to understand why is this happening? BTW, I'm 
using the MESA version 11701, the same used for this particular exercise.

Many thanks in advance for your support.

Best regards,

Roque

PS: The attached inlist file is the one producing the error


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! inlist to generate a standard 1 solar mass model at the deuterium burning birthline

! For the sake of future readers of this file (yourself included),
! ONLY include the controls you are actually using.  DO NOT include
! all of the other controls that simply have their default values.

&star_job

    ! don't begin with a pre-main sequence model
    create_pre_main_sequence_model = .true.

    ! load saved model
    load_saved_model = .false.
    saved_model_name =  'birthline.model'

    ! save a model at the end of the run
    save_model_when_terminate = .true.
    save_model_filename = 'final.model'

    !change_initial_net = .true. ! switch nuclear reaction network
    new_net_name = 'pp_and_cno_extras.net'

    set_rate_c12ag = 'Kunz'
    set_rate_n14pg = 'jina reaclib'

    kappa_file_prefix = 'OP_gs98'
    kappa_lowT_prefix = 'lowT_fa05_gs98' ! for lower temperatures.

    change_lnPgas_flag = .true.
    new_lnPgas_flag = .false.

    set_initial_model_number = .true.
    initial_model_number = 0

    set_uniform_initial_composition = .true.
    initial_h1 =   0.711552
    initial_h2 = 2.6d-5
    initial_he3 = 0.000031
    initial_he4 = 0.269829
    initial_zfracs = 3

    ! Rotation
    new_rotation_flag = .true.
    change_rotation_flag = .true.
    set_initial_omega = .true.
    new_omega =  9.09025d-6

    ! display on-screen plots
    pgstar_flag = .true.

/ !end of star_job namelist


&controls

    varcontrol_target = 1.0d-3 ! timestep for structural change, 10x MESA default

    ! starting specifications
    initial_mass = 1 ! in Msun units
    initial_z = 0.018588

    mixing_length_alpha = 1.816711
    ! options for energy conservation (see MESA V, Section 3)
    use_dedt_form_of_energy_eqn = .true.
    use_gold_tolerances = .true.

    max_age = 4.568d9

    ! disk locking
    use_other_torque = .true.
    x_ctrl(1) = 3.0d6 ! disk lifetime in years
    x_ctrl(2) = 9.090256e-6 ! disk omega in rad/s

    !  Force uniform rotation
    set_uniform_am_nu_non_rot = .true.
    uniform_am_nu_non_rot = 1d20
    
    ! atmosphere
    which_atm_option = 'photosphere_tables'

    ! atomic diffusion
    do_element_diffusion = .false. ! determines whether or not we do diffusion
    diffusion_dt_limit = 7d11 ! no element diffusion if dt < this limit (in seconds)
    diffusion_T_full_on = 1d3
    diffusion_T_full_off = 1d3
    T_mix_limit = 3d4

    diffusion_calculates_ionization = .true.

    diffusion_num_classes = 4 ! number of classes of species for diffusion calculations
    diffusion_class_representative(1) = 'h1'
    diffusion_class_representative(2) = 'he4'
    diffusion_class_representative(3) = 'o16'
    diffusion_class_representative(4) = 'fe56'

    ! in ascending order.  species goes into 1st class with A_max >= species A
    diffusion_class_A_max(1) = 2
    diffusion_class_A_max(2) = 4
    diffusion_class_A_max(3) = 16
    diffusion_class_A_max(4) = 10000

    diffusion_use_isolve = .true.
    diffusion_rtol_for_isolve = 1d-4
    diffusion_atol_for_isolve = 1d-5
    diffusion_maxsteps_for_isolve = 1000
    diffusion_isolve_solver = 'ros2_solver'

    ! Convective tau initialization
    x_ctrl(5) = 0d0
    x_integer_ctrl(5) = 0

/ ! end of controls namelist