I am not sure where to post this, since there is no custodian category, and since most custodian questions are found in the atomate category, I put it here.
In the recent update for VASP6 error handling (I noticed it in version 2021.1.8 in contrast to 2020.4.27), an
IncorrectSmearingHandler class is introduced. I think this is generally a good idea and I want to thank @mkhorton and @rkingsbury for implementing this and the VASP6 update generally so quickly.
However, it is now not possible to use the tetrahedron method with Blöchl corrections (
ISMEAR = -5) for accurate total energy calculations in metals, while it is still recommended to do so in the vasp wiki.
Also the code not only catches tetrahedron smearing with or without Blöchl corrections (-5 and -4) but also -1, -2, and -3, which do different things. These are rare cases and probably not run with custodian anyhow, but if ISMEAR is set to e.g. -2, it is probably best to assume the user knows what they are doing.
I would modify the
check method to detect if a relaxation is performed by reading the NSW flag of the INCAR as well like this:
def check(self): """ Check for error. """ try: v = Vasprun(self.output_filename) # check whether bandgap is zero, tetrahedron smearing was used # and relaxation is performed. if (v.eigenvalue_band_properties == 0 and v.incar.get("ISMEAR", 1) < -3 and v.incar.get("NSW", 0) < 1): return True except Exception: pass return False
Of course this still leaves the issue that forces will be wrong, and one might use the forces of a run even without it being a relaxation. Nevertheless, I feel that this additions limits the functionality as is more than necessary.
I also want to acknowledge that VASP itself prints an on-screen warning message now, even if no relaxation is performed. However, this is a warning, while in custodian, it is treated as an error that must be corrected.
Please let me know if I have to change my approach for static calculations (which I do with
ISMEAR = -5 pretty consistently) or if there might be changes to the