Bugfix for Interstitial Oxidation States (#208)

* Update `core.py`

* Update core.py

* Update test_core.py

Author: kavanase

pymatgen/analysis/defects/core.py

@@ -706,9 +706,9 @@ def name(self) -> str:
     def defect_structure(self) -> Structure:
         """Returns the defect structure."""
         struct: Structure = self.structure.copy()
-        # use the highest value oxidation state among the two most popular ones
+        # use the highest value oxidation state among the most popular ones
         # found in the ICSD
-        inter_states = self.site.specie.icsd_oxidation_states[:2]
+        inter_states = self.site.specie.common_oxidation_states
         if len(inter_states) == 0:
             _logger.warning(
                 "No oxidation states found for %s. "

tests/test_core.py

@@ -119,8 +119,8 @@ def test_interstitial(gan_struct) -> None:
     inter_fpos = [0, 0, 0.75]
     n_site = PeriodicSite(Specie("N"), inter_fpos, s.lattice)
     inter = Interstitial(s, n_site)
-    assert inter.oxi_state == 3
-    assert inter.get_charge_states() == [-1, 0, 1, 2, 3, 4]
+    assert inter.oxi_state == 5
+    assert inter.get_charge_states() == [-1, 0, 1, 2, 3, 4, 5, 6]
     assert np.allclose(inter.defect_structure[0].frac_coords, inter_fpos)
     sc = inter.get_supercell_structure()
     assert sc.formula == "Ga64 N65"