[CP2K-user] [CP2K:17816] Re: magnetic systems in cp2k / AiiDA common workflows

[Krack Matthias (PSI)]

Hi Leopold

You can find an alternate (new) GTH PP for Fe-q16 here<https://github.com/cp2k/cp2k-data/blob/master/potentials/GTH_rev/CP2K/PBE/Fe-q16>. You can use the same TZV2P-MOLOPT-SR-GTH-q16 basis set from BASIS_MOLOPT_UZH, although this basis set has not been specifically optimized for this PP.

Cheers

Matthias

From: cp2k at googlegroups.com <cp2k at googlegroups.com> on behalf of Leopold Talirz <leopold.talirz at gmail.com>
Date: Wednesday, 5 October 2022 at 15:18
To: cp2k <cp2k at googlegroups.com>
Subject: [CP2K:17814] Re: magnetic systems in cp2k / AiiDA common workflows
Hi Matthias,

After chatting with Sasha, he mentions that, for the body-centered cubic Fe structure

 a) the equation of state of the ferromagnetic state (=ground state) fit relatively well with the other codes for 5x5x5 k-points (see https://github.com/aiidateam/aiida-common-workflows/issues/117#issuecomment-799611434), but started to deviate substantially when increasing the number of k-points (!)

 b) the equation of state for the antiferromagnetic state (artificial, not the ground state) was always off, and total magnetization per cell was ~1/4 Bohr magneton per atom above the result for Quantum ESPRESSO.

He mentions he tried a number of things

1.       Fix the total magnetization to 0.
2.       Set a very large k-point grid: 20 20 20
3.       Set MGRID CUTOFF to 1000
4.       Use a very large basis: TZV2P-MOLOPT-SR-GTH-q16
5.       Set EPS_DEFAULT to 1.0E-16
6.       Use different starting magnetization: +4/-4, +2/-2.
He also mentions that one thing he did not try to vary was the pseudopotential, and that you recently added a potential that would make sense to try.
Could you please point me to this potential, and perhaps the basis you would recommend to use with them?

I will then try to rerun the workflow and report results back (including the input files generated).

Cheers!
Leopold

On Wednesday, 5 October 2022 at 14:30:25 UTC+2 Aliaksandr Yakutovich wrote:
Hey.

Please find more info here: https://github.com/aiidateam/aiida-common-workflows/issues/117

Best,
Sasha
On Monday, 3 October 2022 at 15:21:45 UTC+2 Leopold Talirz wrote:
Hi,

I've been looking through the AiiDA common workflows paper [1] and I noticed in table 2 of the SI [2] that both the ferromagnetic and the antiferromagnetic Fe converged to an incorrect ground state with CP2K for "as of yet unknown reasons".

I reached out to coauthor SashaYakutovich to ask whether this was eventually resolved, but it seems like this is not yet the case.

I'd be curious to understand whether someone could help shine some light on what may be underlying this issue, as well as potentially some more general advice on the applicability of cp2k to magnetic systems (both periodic and clusters).

Cheers,
Leopold

P.S. Sasha may be able to provide some more plots / concrete input files as further context.

[1] Common workflows for computing material properties using different quantum engines | npj Computational Materials (nature.com)<https://www.nature.com/articles/s41524-021-00594-6>
[2] 41524_2021_594_MOESM1_ESM.pdf (springer.com)<https://static-content.springer.com/esm/art%3A10.1038%2Fs41524-021-00594-6/MediaObjects/41524_2021_594_MOESM1_ESM.pdf>
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