[Wien] spin + SOC slab issue

[Laurence Marks]

How different are the total energies?

___
Emeritus Professor Laurence Marks (Laurie)
Department of Materials Science and Engineering, Northwestern University
www.numis.northwestern.edu
"Research is to see what everybody else has seen, and to think what nobody
else has thought" Albert Szent-Györgyi

On Sat, Oct 19, 2024, 04:21 pluto via Wien <wien at zeus.theochem.tuwien.ac.at>
wrote:

> Dear Prof. Blaha, dear All,
>
> My sequence is:
>
> instgen_lapw -ask
> init_lapw -sp -b (-prec 1 -ecut 0.999)
>
> Converge without SOC runsp -I (-ec 0.0001 -cc 0.001), save_lapw
>
> init_so_lapw with M=001
>
> Converge calculation with SOC, runsp -p -NI -so (-ec 0.0001 -cc 0.001),
> save_lapw
>
> At this point one can do another init_so_lapw (symmetso it included in
> there) and set M=00-1, and rerun runsp -p -NI -so. However, this
> produces something that is not right, eigenvalues at Gamma are different
> compared to the M=001.
>
> What works is to re-start from the saved non-SOC calculation. Restore
> non-SOC calculation (maybe in a new folder), do init_so_lapw with
> M=00-1, and runsp -orb -p -NI -so. Then the eigenvalues at Gamma are the
> same as in the M001 calculation and things look reasonable.
>
> All this seems to imply that one should not change the direction of M on
> top of previous SOC calculation.
>
> Best,
> Lukasz
>
>
>
>
>
> On 2024-10-18 16:12, Peter Blaha wrote:
> > It is not clear what you actually did. For sure you should not just
> > modify case.inso.
> >
> > You should rerun symmetso (or init_so) when changing the directions
> > and accept the changes.
> >
> > Most likely different symmetry operations will survive for the 2 cases.
> >
> >
> > Am 18.10.2024 um 16:05 schrieb pluto via Wien:
> >> Dear All,
> >>
> >> I am calculating a slab with 44 atoms (22 inequivalent atoms). I have
> >> two equivelent manganese atoms in the slab.
> >>
> >> Space group discovered by sgroup is 164, it has inversion.
> >>
> >> I run "instgen_lapw -ask" and I set Mn spin to u, and all other atoms
> >> to "n" (other atoms are non-magnetic). I monitor this during the SCF
> >> cycle by "grep :MM case.scf", and I am getting around 4.33 for the Mn
> >> moment, a reasonable number.
> >>
> >> The calculation is spin-polarized with SOC. During init_so_lapw I
> >> accept changes made by symmetso.
> >>
> >> I run two separate calculations with magnetization 001 and with 00-1.
> >> This is set in case.inso. Energy (0.0001) and charge (0.001) is
> >> converged.
> >>
> >> The two calculations give different eigenvalues, also at the Gamma
> >> point. Differences are not tiny, they are of the order of 50 meV and
> >> bands look slightly different. Correct me if I am wrong, but I think
> >> this is not physical in this setup.
> >>
> >> Could you please suggest what can be wrong and what can be checked.
> >>
> >> Am I allowed to converge with M = 001, save_lapw, then re-run
> >> init_so_lapw with M=00-1, and then re-run the SCF cycle with -NI? Or
> >> should I always run M=00-1 from the scratch, that is on top of
> >> converged non-SOC calculation?
> >>
> >> Best,
> >> Lukasz
> >>
> >>
> >>
> >>
> >>
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