[Mesa-users] Having difficulty to evolve low mass stars

[Sanskar]

Hello,
 
 I am a first  year PhD student using MESA for first time. I am having difficulty evolving 1M solar mass star to its end stage (white dwarf). The evolution is not getting pass the helium flash point and the solver shows error of min tilmestep reached(10^-13).I  am also attaching the inlist  for this.

! inlist to evolve a 1 solar mass star


&star_job

   create_pre_main_sequence_model = .true.

   change_net=.true.
   new_net_name='pp_and_cno_extras.net'

   ! save a model at the end of the run
   save_model_when_terminate = .true.
   save_model_filename = '2M_final.mod'

   ! display on-screen plots
   pgstar_flag = .true.

/


&eos

/


&kap

   use_Type2_opacities = .true.
   Zbase = 0.014

/


&controls


   ! starting specifications
   initial_mass =1 ! in Msun units
   initial_z = 0.014

   ! when to stop
   fe_core_infall_limit=1d8
   log_L_lower_limit=-1.5

  ! xa_central_lower_limit_species(1) = 'o16'
  ! xa_central_lower_limit(1) = 1d-3
  
   max_model_number=100000

   ! wind
   Reimers_scaling_factor = 0.7
   Blocker_scaling_factor=1.0 
   ! atmosphere

   ! rotation

   ! element diffusion

   ! mlt

   ! mixing
   mixing_length_alpha = 1.8
   use_Ledoux_criterion = .true.
  
   ! Semiconvection
   alpha_semiconvection = 1.0

   ! Thermohaline
   thermohaline_coeff = 1.0
   
   overshoot_scheme(1) = 'step'
  overshoot_zone_type(1) = 'burn_H'
  overshoot_zone_loc(1) = 'core'
  overshoot_bdy_loc(1) = 'top'
  overshoot_f(1) = 0.345
  overshoot_f0(1) = 0.01

  ! Also overshoot above He burning core
  overshoot_scheme(2) = 'step'
  overshoot_zone_type(2) = 'burn_He'
  overshoot_zone_loc(2) = ‘core'
  overshoot_bdy_loc(2) = 'top'
  overshoot_f(2) = 0.1
  overshoot_f0(2) = 0.01

   ! timesteps
   varcontrol_target = 1d-2
  max_timestep_factor = 1.1
  delta_lgL_limit = 0.005
  delta_lgTeff_limit = 0.005
  delta_lgRho_cntr_limit = 0.025
  delta_lgT_cntr_limit = 0.01
  delta_lg_XH_cntr_limit = 0.005
  delta_lg_XHe_cntr_limit = 0.005
  delta_lg_XC_cntr_limit = 0.005
  delta_lg_XNe_cntr_limit = 0.005
  delta_lg_XO_cntr_limit = 0.005
  delta_lg_XSi_cntr_limit = 0.005
 
  delta_lgL_limit=0.01
  delta_lgteff_limit=0.01
  
   min_timestep_limit = 1d-12

   ! mesh
   mesh_delta_coeff = 2.0
   max_allowed_nz = 10000
  
   ! solver
   ! options for energy conservation (see MESA V, Section 3)
    energy_eqn_option = 'eps_grav'
    use_gold_tolerances = .true.

   delta_lgR_limit=0.1

   ! output

/