[Bug]: VASP GAMMA version not used when KSPACING is set in INCAR

[naik-aakash]

Code snippet

No response

What happened?

1. Am trying to run some VASP calculations using atomate2 , where I explicitly set KSPACING in the INCAR
2. Custodian is able to run the VASP job successfully but always uses vasp_std even when KPOINTS resulting from KSPACING is 1x1x1

Expected behaviour

vasp_gam version should be used instead of VASP std.

Potetial fix

Adapt the checks on the following line

custodian/src/custodian/vasp/jobs.py

Line 245 in 880ca8b

if kpts is not None and kpts.style == Kpoints.supported_modes.Gamma and tuple(kpts.kpts[0]) == (1, 1, 1):

Version

2024.6.24

Which OS?

• MacOS
• Windows
• Linux

Log output

No response

[janosh]

did you specify gamma_vasp_cmd? it only auto-switches if it finds the vasp gamma executable and the default name it looks for isn't great since afaik it's more commonly named vasp_gam, not self.vasp_cmd + ".gamma"

custodian/src/custodian/vasp/jobs.py

Lines 127 to 130 in 880ca8b

	gamma_vasp_cmd (str): Command for gamma vasp version when
	auto_gamma is True. Should follow the list style of
	subprocess. Defaults to None, which means ".gamma" is added
	to the last argument of the standard vasp_cmd.

[JaGeo]

KSPACING is the important point. We currently don't see how the code is accounting for this.

[rkingsbury]

KSPACING is the important point. We currently don't see how the code is accounting for this.

Right, IIRC when KSPACING is set, then kpts is None and so the check quoted above would fail.

[naik-aakash]

did you specify gamma_vasp_cmd? it only auto-switches if it finds the vasp gamma executable and the default name it looks for isn't great since afaik it's more commonly named vasp_gam, not self.vasp_cmd + ".gamma"

custodian/src/custodian/vasp/jobs.py

Lines 127 to 130 in 880ca8b

	gamma_vasp_cmd (str): Command for gamma vasp version when
	auto_gamma is True. Should follow the list style of
	subprocess. Defaults to None, which means ".gamma" is added
	to the last argument of the standard vasp_cmd.

Hi @janosh , yes, I did set the gamma_vasp_cmd in the atomate2 config file, and atomate2 is able to use the gamma version automatically when I do not set KSPACING in the INCAR (this results in the KPOINTS file being explicitly generated). Issue occurs only when KSPACING is set.

[esoteric-ephemera]

@naik-aakash @janosh: we'd need to add either a handler to check for when the KSPACING-generated k-points is 1x1x1 and centered at $\Gamma$, or use this formula from the VASP manual to estimate the k-point grid before running VASP

[shyuep]

The VASP gamma code was written in the age before KSPACING was introduced. I am fine with adding logic to check for KSPACING and choosing the gamma version if it results in a 1x1x1 KPOINT. Someone would have to implement it though.