[DFTB-Plus-User] can’t catch magnetism

Bálint Aradi aradi at uni-bremen.de
Wed Feb 10 10:39:56 CET 2021


Dear Toufik,

> Actually, when comparing the non-magnetic structure I get a good
> agreement with DFT calculations.
> When performing a constrained magnetization, It gives me the FM and AM
> structures. But when allowing the total spin to change
> during the run, the system converges to a non magnetic structure for all
> considered alignments (FM, AM, NM).

I think, they may be two reasons, why you do not obtain the ab-initio
result with DFTB. Either, the electronic structure for the spin
polarization is not correctly described for some reasons (e.g. wrong
spin coupling constants?) or in case you also optimize the geometry,
DFTB converges to a geometry which is non-magnetic.

You could also to try to enforce magnetism first, by not letting the
spin relax but keep up-down at a fixed value. Then you can at least
check, whether the band structure is correct, if you enforce the right spin.

Best regards,

Bálint


-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b-aradi/


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