Opened 4 years ago

Last modified 4 years ago

#278 reopened defect - convergence

large H2 aborts with negative populations at high density

Reported by: Gary J. Ferland Owned by: nobody
Priority: major Milestone:
Component: chemical network Version: trunk
Keywords: Cc:


attached aborts fairly quickly with negative level populations

 PROBLEM atom_levelN found negative population, nNegPop=9, atom= H2  lgSearch=T
 -3.11e+04  3.41e+07 -5.62e+04  1.48e+07 -9.76e+03  1.19e+06 -3.94e+02  2.53e+04 -4.48e+00 -1.92e-01  2.01e+02 -3.65e-01  9.45e+01  1.57e+02 -7.07e-02  8.74e+00 -1.85e-02  1.18e-36  3.81e-01  2.12e-01  1.18e-36  1.18e-36  2.14e-03  1.18e-36  1.18e-36  1.09e-03  1.73e-03  1.18e-36  4.17e-04  1.17e-04  1.18e-36  1.18e-36  1.18e-36  5.83e-06  3.50e-06  1.18e-36  1.18e-36  4.46e-08  1.18e-36  1.18e-36  2.31e-07  2.47e-08  3.76e-08  1.18e-36  9.31e-09  3.06e-09  1.18e-36  1.18e-36  1.18e-36  1.18e-36  1.69e-10  1.09e-10  8.41e-11  1.18e-36  1.18e-36  1.87e-12  1.18e-36  1.18e-36  8.05e-12  1.12e-12  1.64e-12  1.18e-36  1.18e-36  4.13e-13  1.60e-13  1.18e-36  1.18e-36  1.18e-36  2.18e-14  1.18e-36  7.10e-15  1.01e-14  4.61e-15  1.18e-36  1.18e-36  1.53e-16  1.18e-36  1.18e-36  5.47e-16  9.93e-17  1.18e-36  1.39e-16  1.18e-36  1.18e-36  1.68e-17  3.67e-17  1.26e-19  1.59e-19  5.23e-20  7.48e-18  1.48e-18  3.39e-19  1.95e-18  3.21e-18  1.05e-18  3.36e-20  5.05e-19  1.13e-19  9.06e-20  3.28e-19  1.48e-19  6.10e-19  2.82e-19  2.38e-19  3.98e-20  1.78e-19  9.87e-20  2.84e-19  5.28e-19  7.71e-20  8.78e-20  3.32e-20  1.35e-18  1.03e-18  3.33e-19  4.08e-19  2.11e-19  5.12e-19  1.55e-20  2.89e-19  2.12e-19  3.30e-20  4.58e-20  1.43e-19  7.46e-20  2.38e-19  1.09e-19  2.58e-20  1.09e-19  1.10e-19  7.29e-20  1.31e-19  4.53e-20  2.15e-19  2.54e-20  1.38e-20  2.96e-20  2.63e-19  2.95e-19  5.63e-19  8.87e-20  4.86e-19  4.37e-19  2.77e-19  5.20e-21  1.56e-20  6.49e-20  1.33e-19  1.69e-20  2.88e-20  4.86e-20  7.88e-20  4.36e-20  1.64e-20  4.23e-20  4.51e-20  3.23e-20  3.83e-20  2.53e-20  1.76e-20  7.27e-20  8.24e-21  4.75e-21  9.30e-21  1.40e-19  1.49e-19  2.99e-20  1.60e-19  1.63e-19  1.59e-21  8.72e-21  1.07e-19  1.77e-20  1.16e-19  5.72e-21  5.12e-20  9.08e-21  6.18e-20  1.79e-20  6.60e-21  1.58e-20  2.37e-20  1.29e-20  2.59e-20  2.27e-20  3.07e-20  9.16e-21  2.08e-20  5.11e-21  1.38e-20  1.23e-20  6.49e-21  5.88e-20  8.84e-21  6.42e-20  4.81e-21  3.17e-22  8.08e-21  3.01e-21  1.30e-21  6.41e-20  5.11e-20  5.76e-20  8.69e-21  2.91e-20  6.58e-21  3.76e-20  2.59e-21  1.10e-20  1.34e-20  4.27e-21  2.05e-20  7.28e-21  1.12e-20  9.18e-21  1.65e-20  1.51e-20  1.49e-20  1.12e-20  1.08e-20  8.21e-21  6.26e-21  1.61e-22  1.41e-20  3.60e-21  6.96e-21  5.77e-22  3.08e-21  1.72e-21  6.52e-21  3.78e-21  6.88e-22  1.95e-20  1.54e-21  2.05e-20  8.22e-21  1.37e-20  1.59e-20  3.69e-21  7.50e-21  4.36e-21  9.81e-21  1.03e-21  1.47e-21  4.63e-21  7.37e-21  2.09e-21  8.42e-23  5.24e-22  2.69e-21  2.97e-21  3.04e-22  3.03e-21  1.87e-21  2.49e-21  7.93e-22  8.57e-22  1.04e-21  5.32e-21  1.63e-21  3.02e-22  2.14e-21  1.32e-21  5.94e-22  1.07e-21  2.78e-22  2.94e-21  2.63e-21  3.94e-21  1.88e-21  2.60e-21  4.29e-22  6.98e-22  2.07e-23  1.34e-22  1.14e-21  9.90e-22  1.89e-21  8.89e-23  2.38e-22  2.12e-22  6.37e-22  1.09e-22  1.17e-21  2.31e-22  2.73e-22  3.02e-22  3.50e-22  2.05e-22  2.67e-22  7.78e-23  3.54e-22  1.32e-22  5.55e-24  6.02e-23  2.36e-23  2.31e-22  1.12e-22  1.91e-22  8.59e-22  7.81e-23
 H2_Level_low_matrix called atom_levelN which returned negative populations.
 PROBLEM  ConvFail 1, H2 population not converged iteration 1 zone 0 fnzone 0.00 chem eft chg 0.0597701 0


Change History (5)

comment:1 Changed 4 years ago by Gary J. Ferland

trunk r8919

comment:2 Changed 4 years ago by Gary J. Ferland

coronal equilibrium 2.7
hden 8
abundance primordial
atom H2
stop zone 1

comment:3 Changed 4 years ago by Ryan Porter

Resolution: fixed
Status: newclosed

"Fixed" at r8995. Solution was accidental (not directed at this problem in particular) and could be unstable. Sim added to test suite as auto/ Can safely close ticket now.

comment:4 Changed 4 years ago by Gary J. Ferland

Resolution: fixed
Status: closedreopened

comment:5 Changed 4 years ago by Gary J. Ferland

This sim does run clean on gcc / cloud9 but fails with very different answers on other compilers - radegund / gcc is a good example. It was discussed extensively in private emails between Ryan, Robin, Phillip, Peter, and me, around 2014 May, June

The sim has no source of ionization since primordial gas has no cosmic ray background and the CMB is cool. (The sim is happy with the CRB included). As a result the correct electron density is zero, which the code hunts for, but does not "find" since convergence is determined by the ratio (Eden_true - Eden_current)/Eden_true and Eden_true ->0.

A second problem is that the gas is fully molecular. With no ions or atoms, there is no ortho - para conversion by exchange collisions. As a result the OP ratio is indeterminate.

I am not too concerned about the second problem since this situation cannot happen in this universe. It is possible to ask the code to compute an impossible situation. We are hunting for a steady-state solution but the time scales are longer than the age of the universe at that redshift. Calculations which follow the time-dependent behavior find a trace amount of H0 and H+ at this epoch, so the OP conversion is well defined. We are asking a question that does not have an answer.

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