Easy use of custom abundances

[erwanp]

🎯 Describe what you'd like

Make it easy to choose custom isotope abundances.
Very relevant for non-Earth atmospheres !

💡 Possible implementations

• Retrieval is done in loader.py which loads HITRAN's molparams.txt. Quite easy to override this at runtime (only warning : make sure the _fetch_molecular_parameters is not re-called several times

Impact on calculations :

• at non-eq, the calculation of the emission uses the abundance. So nothing to do; the custom abundances will be used directly.

• the calculation of absorption is based on Linestrengths. Linestrengths scale linearly with the abundance; so a correction ratio should be introduced. ( it is isotope-based and would be efficiently implemented with the map(dict) approach used by @gagan-aryan for partition functions Qgas).

  

  Corrections needed in linestrength_eq and linestrength_noneq

---

_{Tip : you can vote for New Features on https://feathub.com/radis/radis}