missing molecules

[ajwheeler]

MARCS (and Turbospectrum, which uses the same list) include 527 molecules. Korg includes 271, of which 8 are not in MARCS. Of the ones which are not in Korg,

• 21 are positively charged atomic ions, e.g. Al+. I don't know why these are included as molecules, and Korg models them as it does all positive atomic ions.
• 3 (H-, F-, Cl-) are negatively charged atomic ions, which Korg does not include in it's chemical equilibrium calculations. I think this is very unlikely to be a problem.
• 45 are molecular ions, which Korg currently doesn't support.
• 195 are neutral molecules that we don't include
  • 133 of these have at least 3 atoms, including 3 which have 7, one more than Korg currently supports.

A lot of this data is from Irwin 1981 and Saubal and Tatum 1984, but there have been a couple dozen or so additions over the years according to the notes at the top of the file. I think we might be in the unfortunate situation that the only reasonably up-to-date and complete lists of K and D00 values are the SME and Turbospectrum/MARCS datafiles.

It's hard to tell which of these molecules exist in large quantities in stellar atmospheres without data to do calculations. As a test, it may be helpful to try out the Ks from the Turbospectrum datafile, but there's no way to know the effect of charged molecules without implementing support for them.

This issue is especially relevant in light of the fact that chemical equilibrium convergence is very effected by the list of molecules included. This also suggests that the molecular ions are the culprit. It's probably important to get them working.

[ajwheeler]

Closing this because it's out of date (Korg now supports charged molecules), and I no longer believe this is an accuracy bottleneck.