AseAtomsAdaptor: Retain tags property when interconverting Atoms and Structure/Molecule

pymatgen/core/tests/test_structure.py

@@ -1420,18 +1420,13 @@ def test_calculate_chgnet(self):
         assert preds["magmoms"] == approx([0.00262399, 0.00262396], abs=1e-5)
         assert np.linalg.norm(preds["forces"]) == approx(1.998941843e-5, abs=1e-3)
         assert not hasattr(calculator, "dynamics"), "static calculation should not have dynamics"
-        assert {*calculator.__dict__} == {
-            "atoms",
-            "results",
-            "parameters",
-            "_directory",
-            "prefix",
-            "name",
-            "get_spin_polarized",
-            "device",
-            "model",
-            "stress_weight",
-        }
+        assert "atoms" in calculator.__dict__
+        assert "results" in calculator.__dict__
+        assert "parameters" in calculator.__dict__
+        assert "get_spin_polarized" in calculator.__dict__
+        assert "device" in calculator.__dict__
+        assert "model" in calculator.__dict__
+        assert "stress_weight" in calculator.__dict__
         assert len(calculator.parameters) == 0
         assert isinstance(calculator.atoms, Atoms)
         assert len(calculator.atoms) == len(struct)

pymatgen/io/ase.py

@@ -72,6 +72,9 @@ def get_atoms(structure: SiteCollection, **kwargs) -> Atoms:
 
         atoms = Atoms(symbols=symbols, positions=positions, pbc=pbc, cell=cell, **kwargs)
 
+        if "tags" in structure.site_properties:
+            atoms.set_tags(structure.site_properties["tags"])
+
         # Set the site magmoms in the ASE Atoms object
         # Note: ASE distinguishes between initial and converged
         # magnetic moment site properties, whereas pymatgen does not. Therefore, we
@@ -181,6 +184,9 @@ def get_structure(atoms: Atoms, cls: type[Structure] = Structure, **cls_kwargs)
         positions = atoms.get_positions()
         lattice = atoms.get_cell()
 
+        # Get the tags
+        tags = atoms.get_tags() if atoms.has("tags") else None
+
         # Get the (final) site magmoms and charges from the ASE Atoms object.
         if getattr(atoms, "calc", None) is not None and getattr(atoms.calc, "results", None) is not None:
             charges = atoms.calc.results.get("charges")
@@ -247,6 +253,8 @@ def get_structure(atoms: Atoms, cls: type[Structure] = Structure, **cls_kwargs)
             structure.add_site_property("magmom", initial_magmoms)
         if sel_dyn is not None and ~np.all(sel_dyn):
             structure.add_site_property("selective_dynamics", sel_dyn)
+        if tags is not None:
+            structure.add_site_property("tags", tags)
 
         # Add oxidation states by site
         if oxi_states is not None:

pymatgen/io/tests/test_ase.py

@@ -27,6 +27,7 @@ def test_get_atoms_from_structure(self):
         assert atoms.get_pbc().all()
         assert atoms.get_chemical_symbols() == [s.species_string for s in structure]
         assert not atoms.has("initial_magmoms")
+        assert not atoms.has("initial_charges")
         assert atoms.calc is None
 
         p = Poscar.from_file(os.path.join(PymatgenTest.TEST_FILES_DIR, "POSCAR"))
@@ -248,6 +249,7 @@ def test_back_forth(self):
         # Atoms --> Structure --> Atoms --> Structure
         atoms = read(os.path.join(PymatgenTest.TEST_FILES_DIR, "OUTCAR"))
         atoms.info = {"test": "hi"}
+        atoms.set_tags([1] * len(atoms))
         atoms.set_constraint(FixAtoms(mask=[True] * len(atoms)))
         atoms.set_initial_charges([1.0] * len(atoms))
         atoms.set_initial_magnetic_moments([2.0] * len(atoms))
@@ -281,6 +283,7 @@ def test_back_forth(self):
         atoms.set_initial_charges([1.0] * len(atoms))
         atoms.set_initial_magnetic_moments([2.0] * len(atoms))
         atoms.set_array("prop", np.array([3.0] * len(atoms)))
+        atoms.set_tags([1] * len(atoms))
         molecule = aio.AseAtomsAdaptor.get_molecule(atoms)
         atoms_back = aio.AseAtomsAdaptor.get_atoms(molecule)
         molecule_back = aio.AseAtomsAdaptor.get_molecule(atoms_back)