Implemented a converter from a CRYSTAL23 output file to the TREX-IO format.

[kousuke-nakano]

Implemented a converter from a CRYSTAL23 output file to the TREX-IO format.

Implemented a converter from a CRYSTAL23 output file [https://www.crystal.unito.it] to the TREX-IO format.

How to use this converter:

• python src/trexio_tools/converters/crystal_to_trexio.py -c data/crystal23_mgo_lda.out

Supports:

• Only PBC calculations are supported.
• All RHF, UHF, and ROHF are supported.
• Both orthorhombic and non-orthorhombic cells are supported.
• Users should specify the spin state (i.e., 2S+1). The default is 1.
• CRYSTAL23 is a commercial software package. One should purchase its license to use it [https://www.crystal.unito.it].

[q-posev]

Thanks @kousuke-nakano for your hard work!

Please do not merge this MR yet, I need to do some reorganization so that converter is compatible with convert-from like others. I will push to this branch when it is ready.

[kousuke-nakano]

Dear @q-posev, could I merge this pull request?

[q-posev]

Sorry for my lare response @kousuke-nakano ! I did not have time integrate your converter so that it can be used via convert-from. It is a relatively simple change (just need to call you crystal_to_trexio in convert_from and add a CLI option for crystal code like I did back in the days for your PySCF converter in #15 .

I guess the goal is to use your converter via convert-from, right? Maybe I can have a look this weekend, should be too much work to add it.

[q-posev]

OK, @kousuke-nakano turns out I cannot push to this PR because it's from your fork.
I will merge this PR and prepare another one to integrate your converter into convert-from.
Thanks again, Kousuke!

[q-posev]

Approved

[kousuke-nakano]

Thanks! @q-posev