Core hole calculations with MOM / IMOM

[msnik1999]

Adding functionality for modifying the orbital occupancies to allow core hole calculations, e.g. for XPS core binding energy calculations. @lratcliff
Also adding MOM/IMOM methods to assist these calculations.

[msnik1999]

ToDo:

• tests for unrestricted MOM/IMOM calculations
• output depending on print level

[ilfreddy]

1. To make the test pass, you should first rebase so that you make sure your code also is compiling&testing the macos-12 build
2. We should see what is missing to bring this from draft to mergeable PR
3. Does this PR depend on the the corresponding one (fractional occupation numbers) in mrcpp?

[msnik1999]

1. To make the test pass, you should first rebase so that you make sure your code also is compiling&testing the macos-12 build

   2. We should see what is missing to bring this from draft to mergeable PR

   3. Does this PR depend on the the corresponding one (fractional occupation numbers) in mrcpp?

I think I addressed all issues and problems. This PR is dependent on the corresponding one in MRCPP.

[stigrj]

The MRCPP PR is now merged, so you can update the GIT_TAG in external/upstream/fetch_mrcpp.cmake to the latest on master. Also, for the failing exchange issue, you can add an explicit exception somewhere in the initialization that fails whenever someone is trying to run MOM calculations with exact exchange. Then open an issue that explains the problem.

[msnik1999]

The MRCPP PR is now merged, so you can update the GIT_TAG in external/upstream/fetch_mrcpp.cmake to the latest on master. Also, for the failing exchange issue, you can add an explicit exception somewhere in the initialization that fails whenever someone is trying to run MOM calculations with exact exchange. Then open an issue that explains the problem.

Done

[Gabrielgerez]

Ill try resolving the conflict and we can probably just merge it after that