I was trying to use the one-zone burner at constant density from $MESA_DIR/net/test , with an initial composition of pure helium, logT = 9 and logRho = 5, and I noticed that the temperature didn't evolve much (changed only by 1d-8) when I used a net like mesa_125.net . The simplest net that shows this problem is one with only he4 and c12. However, the temperature does evolve (logT changes by 0.2ish) if I use approx21.net, or if I use other nets with use_3a_fl87 = .true. (e.g., by adding the line g% use_3a_fl87 = .true. near line 236 in $MESA_DIR/net/test/mod_one_zone_burn.f90).
I dug deeper with the he4+c12-only net. I added some print statements and found that eps_nuc returned by eval_net (called by burner_derivs in $MESA_DIR/net/private/net_burn_const_density.f90) is zero , while dxdt(:) gives the right rates. I should also note that eval_net is also called by burner_jakob but returns the right eps_nuc.
I used the same conditions (pure He, logT=9, logRho=5 and he4+c12-only net) with sample_net (which also lives in $MESA_DIR/net/test) and got the right eps_nuc, so I think this behavior seems to only affect the one-zone burner. I'm using 24.08.1, so reverse 3a and detailed balance with >2 reactants are also not the problem.
I was trying to use the one-zone burner at constant density from $MESA_DIR/net/test , with an initial composition of pure helium, logT = 9 and logRho = 5, and I noticed that the temperature didn't evolve much (changed only by 1d-8) when I used a net like mesa_125.net . The simplest net that shows this problem is one with only he4 and c12. However, the temperature does evolve (logT changes by 0.2ish) if I use approx21.net, or if I use other nets with use_3a_fl87 = .true. (e.g., by adding the line
g% use_3a_fl87 = .true.near line 236 in$MESA_DIR/net/test/mod_one_zone_burn.f90).I dug deeper with the he4+c12-only net. I added some print statements and found that
eps_nucreturned byeval_net(called byburner_derivsin$MESA_DIR/net/private/net_burn_const_density.f90) is zero , whiledxdt(:)gives the right rates. I should also note thateval_netis also called byburner_jakobbut returns the righteps_nuc.I used the same conditions (pure He, logT=9, logRho=5 and he4+c12-only net) with sample_net (which also lives in
$MESA_DIR/net/test) and got the righteps_nuc, so I think this behavior seems to only affect the one-zone burner. I'm using 24.08.1, so reverse 3a and detailed balance with >2 reactants are also not the problem.I'm attaching my inlist and net here. he4_and_c12.net.txt inlist_one_zone_burn_pureHe.txt
Any pointers/suggestions are greatly appreciated!
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