Merge pull request #275 from janosh/LargeSigmaHandler-fallback-to-ism…

…ear=0

`LargeSigmaHandler` set `ISMEAR=0` if sigma reaches `0.02` minimum

custodian/vasp/handlers.py

@@ -1285,6 +1285,15 @@ def correct(self):
                     "action": {"_set": {"SIGMA": sigma - 0.06}},
                 }
             )
+        else:
+            # https://vasp.at/wiki/index.php/ISMEAR recommends ISMEAR = 0 if you have
+            # no a priori knowledge of your system ("then always use Gaussian smearing"
+            actions.append(
+                {
+                    "dict": "INCAR",
+                    "action": {"_set": {"ISMEAR": 0, "SIGMA": 0.05}},
+                }
+            )
 
         VaspModder(vi=vi).apply_actions(actions)
         return {"errors": ["LargeSigma"], "actions": actions}