Fixing Crashes on Transition to RSG

Diagnostic:

• code crash during central helium burning, usually during an early stage for solar metallicity, may be later for Pop III stars

• outermost few zone are alreay convective; this is barely visible on mass coordianate plot, you need to plot as a function of radius

  p 132 1
  plot 1
  

  often you will see up to tow small convection zone

• the code tries to reduce timestep by a lot - you will see many backups

• the time step may already be very small

Possible solutions:

• if the time step is not yet small, try to allow more backups; it may require more than 10 backups, but should definitvely not be more than 20

  p 52 20
  

• if the time step is already small, the code may need to recover.

  • The first thing to try is to change correction factor during iteration, fmin (p 375). Set it to a smaller number, e.g.,

    p 375 .1
    

  • Next, try to increase linear viscosity, q1fac (p 13) to a high number, e.g.,

    p 13 1000.
    

    Warning

    Do not forget to set it back to the original value, usually 0.1 during normal evolution, when the code has recovered to a large time step!

    p 13 .1