Fix bug in UHF gradient code

[fevangelista]

Description

This PR fixes a bug in the UHF gradients for systems with no beta electrons (1-electron systems).
On line 463 of psi4/src/psi4/scfgrad/jk_grad.cc I couldn't avoid skipping this operation because this buffer is read somewhere else (and it practically does not matter for 1-electron systems).

// > Stripe < //
psio_->write(unit_b_, "(A|ij)", (char*)Aijp[0], sizeof(double) * np * nb * nb, next_Aijb, &next_Aijb);

Todos

• Fixes logic in scf_grad code

Checklist

• Added a test of the UHF gradient for H2+.
• All or relevant fraction of full tests run

Status

• Ready for review
• Ready for merge

[JonathonMisiewicz]

One thing that needs to be added: update tests/CMakeLists.txt with the name of your new test.

[loriab]

I added to the tests/CMakeLists directly.