[Mesa-users] How do I change the initial_z value of a star module

[jk00225 at surrey.ac.uk]

Dear all,


I'm using mesa-r5118 on Ubuntu (16.04  LTS) with mesasdk (version 20141023) and have encountered an issue with trying to change the initial_z value of my star.  I'm currently using MESA for a final year project at University and am using the inlist_flash inlist of the "Hydrogen Burning on Accreting White Dwarfs: Stability, Recurrent Novae, and the Post-Nova Supersoft Phase" paper from http://cococubed.asu.edu/mesa_market/inlists.html (5th from bottom). I'm trying to expand upon this by changing the metallicity of the star, and seeing how the metallicity will change the evolution of the star. However, when I try to change the metallicity it fails to converge.  I've currently added the following commands to the following namelists.


&star_job

change_initial_Z = .TRUE.
change_z = .true.
new_Z = 0.005

&controls
initial_z = 0.005

When I run MESA I get the following lines of output before the program stops:

 All this and more are saved in the LOGS directory during the run.
                                         set_tau_factor    3.0000000000000000D+01
load saved model /home/james/MESA/nova/HB_on_WD_bw/steady_burning_models/1.00Msun_Tc_3e7_init.mod

 set_net cno_extras_o18_to_mg26_plus_fe56.net
 set_initial_age   0.0000000000000000
 set_initial_dt   1.0000000000000000E-003
 set_initial_model_number           0
 change to cno_extras_o18_to_mg26_plus_fe56.net
 number of species =          24
 change_v_flag = T
                                               change_Z    5.0000000000000001D-03
                                                  new z    5.0000000000010635D-03
                                       change_initial_Z    5.0000000000000001D-03
                                                  new z    5.0000000000001927D-03
 net name cno_extras_o18_to_mg26_plus_fe56.net
 v_flag = T
                                             tau_factor    3.0000000000000000D+01
                         which_atm_option: grey_and_kap
                      use small_mtx_decsol bcyclic_dble          24         100
 kappa_file_prefix gn93
 kappa_lowT_prefix lowT_fa05_gs98
   eos_file_prefix mesa
                                        OMP_NUM_THREADS           4


MESA runs for about 27 iterations then stops with the following information:

                                                     dt    6.1216685478627150D-13
                                     min_timestep_limit    9.9999999999999998D-13

 stopping because of convergence problems dt < min_timestep_limit


terminated evolution: convergence problems

termination code: min_timestep_limit

I've tried using relax_Z = .true. but that doesn't seem to change anything as I get the same error. I tried using the command relax_initial_z but that doesn't exist within this version. Is there a way to change the initial_Z value of the module I'm using? Also, could I ask why the initial_Z is limited to 0 to 0.04?

Many Thanks for the help,
James


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