Pourbaix: fix filtering extra elements

[rkingsbury]

Fixes bug in which get_pourbaix_entries was not properly filtering out extra elements (i.e., solid entries included in the internal phase diagram because they are reference solids for ions, but that are not part of the originally-supplied chemical system)

Contributor Checklist

• I have run the tests locally and they passed.
• I have added tests, or extended existing tests, to cover any new features or bugs fixed in this PR

[rkingsbury]

@mkhorton this PR fixes the bug you found related to element filtering. However, in the course of debugging I noticed that the energies of all Pourbaix entries returned by this package differ from those returned by the legeacy get_pourbaix_entries method in pymatgen. I added a test here to verify that the ion entries are being positioned correctly relative to the solid entries; the difference seems to arise from the solid entries themselves.

For example, the legacy client returns the following energy_per_atom

('mp-2414', 0.37806497411458206)
('mp-24118', 0.9102134379934201)

while the new client (in this package) returns

('mp-2414', 0.503819126302082)
('mp-24118', 0.9366894532565775)

It's unclear why this is happening, as all the arguments related to corrections, etc. are identical between the old and new clients.

This may be related to collection differences? Because If I just examine the solid entry using get_entry_by_material_id, I get

[('mp-2414', -6.448287344166668)]

from the legacy client and

[('mp-2414', -6.322537344166668)]

from the new client.

[rkingsbury]

Also, all CI tests seem to be failing due to a missing API key:

>           raise MPRestError(
                f"REST query returned with error status code {response.status_code} "
                f"on URL {response.url} with message:\n{message}"
            )
E           mp_api.core.client.MPRestError: REST query returned with error status code 401 on URL https://api.materialsproject.org/xas/?_fields=edge&edge=K&_limit=1 with message:
E           Response {
E             "message":"No API key found in request"
E           }

src/mp_api/core/client.py:652: MPRestError

[munrojm]

No API key is normal. If the tests pass locally, I can merge and it should be fine. Let me know when you are good to go.

Also, just an FYI that the difference in the energy for that material appears to be from the removal of an incorrect anion correction applied to sulfur in the new data.

[rkingsbury]

Also, just an FYI that the difference in the energy for that material appears to be from the removal of an incorrect anion correction applied to sulfur in the new data.

OK, that makes sense. I was primarily looking at sulfur-containing systems so that must have been the origin of the discrepancy. I checked some other systems and the differences were smaller or non-existent. I'm good.

[mkhorton]

Thanks for taking a look and offering this fix @rkingsbury!

[mkhorton]

This list() is redundant