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Fully molecular limit problem

title crash with negative molecular populations
cosmic rays, background
*trace molecules
black 1000 linear
energy density 10 linear
hden 4
constant density
stop zone 1

Cloudy uses complete linearization to obtain solutions.  The code is designed to go to the fully molecular limit by a smooth transition from the ionized case.  This model represents a category of problems.  The inital solution is fully molecular, and, were the cosmic rays not there, would have no atomic hydrogen at all.  The code will not be able to find an inital solution.

The fix will require better care in the approach to the initial solution in the fully molecular case.  This problem is now on the back burner since fully molecular environments are seldom time-steady (Bertoldi, F., & Draine, B. T. 1996, ApJ, 458, 222).

Last changed 04/05/03.
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Copyright 1978-2003 Gary J. Ferland