Negative Ca I populations
the attached sim fails with
PROBLEM atom_levelN found negative population, nNegPop=7, atom=Ca 1 lgSearch=F Te= 8.71e+03 fnzone 0.00 Absolute: 1.30e-03 9.59e-08 2.80e-07 4.41e-07 -3.96e-06 -6.56e-06 -9.09e-06 1.92e-05 3.11e-09 1.11e-11 4.28e-07 -4.30e-10 -5.75e-10 -4.07e-10 -7.09e-10 Relative: 9.99e-01 7.38e-05 2.15e-04 3.39e-04 -3.05e-03 -5.05e-03 -6.99e-03 1.48e-02 2.39e-06 8.52e-09 3.30e-04 -3.31e-07 -4.43e-07 -3.13e-07 -5.46e-07 PROBLEM in dBase_solve, atom_levelN returned negative population . [Stop in dBase_solve at ../species2.cpp:656, something went wrong]
The atomic data for Ca I are sparse. cacrash.inThere are few real data. NIST has energy levels but there are no collision strengths - so this is a "baseline" model where we used g-bar for electron CS. Even the As are very limited - only E1 mostly connecting higher levels. There are few transitions within the lowest fifteen levels, our default size.
There are other problems. Ca I has a very low ionization potential and so will only be present where the gas is cool since ionizing radiation must be blocked. To do a proper model we would need neutral collisions at low temperatures. Currently, we only monitor one of its lines in blr_n13_p18_Z20.in "Ca 1" 4226.73. That is the 1-9 transition.
The failure occurs with C17_branch and likely with HEAD once we get past the He-like high Z problem