Quadrupole moment loss

[chrisiacovella]

Pull Request Summary

This PR will add in the quadrupole moment calculation (from the per atom charges) and have this be an option for uses in the training loss.

Questions

Right now the way this was set up initially, dipole moment will only be calculated as part of the losses. quadrupole moment is implemented the same way. That means, in inference mode, these properties are no output by the model. Right now, users can take the partial charges predicted by the model, and then compute these properties on their own. While this is slightly annoying when doing testing, these properties aren't necessarily something used directly in simulations and such, so it makes sense for them not to be returned. I'm not sure it would be worth it to modify this such that these properties are also registered during inference (from the production side of things, if we won't use a quantity, there is no sense wasting computational time computing it), and if they can just be toggled on/off (toggled on when needed for testing).

Key changes

Notable points that this PR has either accomplished or will accomplish.

• Add in quadrupole moment code
• add in as loss option
• add as an option in the parameter models
• Add in tests for quadrupole moment

Associated Issue(s)

• quadrupole moment calculation #381

Pull Request Checklist

• Issue(s) raised/addressed and linked
• Includes appropriate unit test(s)
• Appropriate docstring(s) added/updated
• Appropriate .rst doc file(s) added/updated
• PR is ready for review

[codecov-commenter]

Codecov Report

❌ Patch coverage is 98.03922% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.91%. Comparing base (1f89c84) to head (bbfbae3).

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