Use vasp_gam for 1x1x1 k-point grids regardless of whether it is gamma-centered or not (#375)

Author: Andrew-S-Rosen

src/custodian/vasp/jobs.py

@@ -1005,15 +1005,10 @@ def _gamma_point_only_check(vis: VaspInput) -> bool:
         # Prevent VASP gamma from being run on DFPT tasks.
         return False
 
-    if (
-        kpts is not None
-        and kpts.style == Kpoints.supported_modes.Gamma
-        and tuple(kpts.kpts[0]) == (1, 1, 1)
-        and all(abs(ks) < 1.0e-6 for ks in kpts.kpts_shift)
-    ):
+    if kpts is not None and tuple(kpts.kpts[0]) == (1, 1, 1) and all(abs(ks) < 1.0e-6 for ks in kpts.kpts_shift):
         return True
 
-    if (kspacing := vis["INCAR"].get("KSPACING")) is not None and vis["INCAR"].get("KGAMMA", True):
+    if (kspacing := vis["INCAR"].get("KSPACING")) is not None:
         # Get number of kpoints per axis according to the formula given by VASP:
         # https://www.vasp.at/wiki/index.php/KSPACING
         # Note that the VASP definition of the closure relation between reciprocal

tests/vasp/test_jobs.py

@@ -201,16 +201,18 @@ def test_gamma_checks(self) -> None:
 
         vis = MPRelaxSet(structure=structure)
         assert vis.kpoints.kpts == [(1, 1, 1)]
-        assert vis.kpoints.style.name == "Gamma"
         assert _gamma_point_only_check(vis.get_input_set())
 
         # no longer Gamma-centered
-        vis = MPRelaxSet(structure=structure, user_kpoints_settings=Kpoints(kpts_shift=(0.1, 0.0, 0.0)))
+        vis = MPRelaxSet(structure=structure, user_kpoints_settings=Kpoints(kpts=[2, 1, 1]))
         assert not _gamma_point_only_check(vis.get_input_set())
 
-        # have to increase KSPACING or this will result in a non 1 x 1 x 1 grid
-        vis = MPRelaxSet(structure=structure, user_incar_settings={"KSPACING": 0.5})
-        assert _gamma_point_only_check(vis.get_input_set())
+        vis = MPRelaxSet(structure=structure, user_kpoints_settings=Kpoints(kpts_shift=(0.1, 0.0, 0.0)))
+        assert not _gamma_point_only_check(vis.get_input_set())
 
-        vis = MPRelaxSet(structure=structure, user_incar_settings={"KSPACING": 0.5, "KGAMMA": False})
+        # KSPACING-related checks
+        vis = MPRelaxSet(structure=structure, user_incar_settings={"KSPACING": 0.005})
         assert not _gamma_point_only_check(vis.get_input_set())
+
+        vis = MPRelaxSet(structure=structure, user_incar_settings={"KSPACING": 50})
+        assert _gamma_point_only_check(vis.get_input_set())