Should atomic_symbol return Symbol or ChemicalSpecies ?

[cortner]

No description provided.

[rkurchin]

My intuitive expectation based on the name would be Symbol – what's the particular argument for it returning ChemicalSpecies?

I guess this also relates to @tjjarvinen's suggestion here and for me brings up the question of whether, if we indeed go the Symbol route, do we want to effectively restrict valid outputs to be actual symbols on the periodic table or broaden to (for example) anything that would be valid in a PDB file?

[cortner]

ChemicalSpecies was intended as a more "rigorous" replacement of a simple Symbol from 0.3.

More generally, there are now a lot of very similar functions in AtomsBase that maybe need to be revisited together.