Atomic Static Dipole Polarizabilities

[PaulWAyers]

It would be good to add that feature if not yet supported. See the reference data here.

[gabrielasd]

@PaulWAyers @marco-2023 @msricher
I'll like to know your thoughts in regards to the issue raised in PR #101
and I'll cp here part of the comment made in the PR:

">With regards to the issue: ``During testing, I observed an issue in the code: it is loading compiled data instead of data directly from the files."

This to me is the expected behaviour based on the current implementation. Instances of the Species class for a given database, only show information loaded from already compiled data. So to have the updated polarizabilities available for all databases through instances of the Species class we will need to recompile the neutral species for each database."

I think we knew that if the Species properties were modified one would need to recompile the databases in order to have those properties available through the Species class.

To me one (dirty alternative) to the task of recompiling the neutral species though all databases would be to only recompile the NIST database given that this is the one that takes lowest disk space (since it does not include any density properties).

[PaulWAyers]

Is it very painful to compile the data? I wonder if this is just something that is part of the workflow when a new species properties is added. That isn't something that is terribly problematic, and I can imagine that one may (eventually) want dipole polarizabilities at other levels of theory too.

[marco-2023]

My thoughts at the beginning were to not compile this data at all. This data (periodic) is prone to change every few years. I think a good compromise is to just load the atomic properties once (as it is done now before compiling the data) at the moment when AtomDB is loaded and complement the data with the rest of the properties that are compiled (that should never change).

In this way, the parsing of the elements data file will be done only once, and from then on, this data is accessed from memory.