[Wien] spin + SOC slab issue

[pluto]

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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