DRAFT: Move periodic table definition to dictionary

[nils-wittemeier]

As the title states, this PR moves the definition of the periodic table to a new datatype.

The following change are made:

• Adds new dependency 'fhash'
• Adds a new data type isotopes.
• Moves the definition of isotope masses and abundance to 'params' module
• Moves definition of precisions (r64, r128, i64) to new module called 'precision'. I took the liberty of splitting this part of params into a new module, to avoid circular imports. Otherwise m_isotopes requires r64 from params and params requires the new datatype isotopes from m_isotopes. It seems like similar issues could arise in the future in other contexts.

Before merge:

• replace existing queries in old periodic table with queries in the new table
• remove old table
• test

[nils-wittemeier]

I briefly checked that everything compiles, but had some MPI-related issues when running tests, that I'll have to look into.

[nils-wittemeier]

It might be worth thinking of whether quantities like the average mass should be calculated in the constructor of the isotopes type, or whether to implement a function that returns the average mass.

[nakib]

Dear Nils. Thanks for the contribution, really appreciate it. I left some comments. Would you please consider these? One crucial point: the CI broke since the type check in lookup_periodic_table caught an invalid type. Would be great if you could check this. Thanks a lot!

[nakib]

It might be worth thinking of whether quantities like the average mass should be calculated in the constructor of the isotopes type, or whether to implement a function that returns the average mass.

This is a good point. Since there is now two ways to think about the atomic mass -- virtual crystal approximation (VCA) or dominant isotope background (DIB) https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.165201 -- it would be good to have one or both of these masses served by someone on demand. Now whether this should be the crystal or the isotopes type is something to think about. I was thinking that isotopes should be a private type inside the crystal_module.

[nils-wittemeier]

Thank you for the feedback.

I agree with everything.

I will work on it soon.

[nakib]

I think I found the issue. You might just have to do call periodic_table%get_raw(key(element), raw_data) -> call periodic_table%get_raw(key(trim(element)), raw_data) in lookup_periodic_table.

[nils-wittemeier]

I think I found the issue. You might just have to do call periodic_table%get_raw(key(element), raw_data) -> call periodic_table%get_raw(key(trim(element)), raw_data) in lookup_periodic_table.

Yes, this is what I suspected. I will check tomorrow and update the branch.

[nakib]

Nils, everything is in order. Thanks a lot for your contribution.