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

toufik esssakhri tousak at hotmail.fr
Wed Feb 10 09:59:08 CET 2021


Dear Dr.  Balint,

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).

Regards,
Toufik


________________________________
De : DFTB-Plus-User <dftb-plus-user-bounces at mailman.zfn.uni-bremen.de> de la part de Bálint Aradi <aradi at uni-bremen.de>
Envoyé : mardi 9 février 2021 16:26
À : dftb-plus-user at mailman.zfn.uni-bremen.de <dftb-plus-user at mailman.zfn.uni-bremen.de>
Objet : Re: [DFTB-Plus-User] can’t catch magnetism

Dear Toufik,

hard to say what happens here. Your input seems to be OK at the first
glance. Try to compare the band structure with the ab initio DFT
reference. You may get a guess, why no spin polarization occurs in DFTB.

Best regards,

Bálint


On 08.02.21 14:10, toufik esssakhri wrote:
> Dear all,
>
> I can’t catch magnetismof a 2D material. Experiments and DFT show a
> ferromagnetic alignment with about 2.6 and 2.8 muB.
>
>
> Nr. of electrons (up): 23.99886262
>
> Atom populations (up)
>
> Atom Population
>
> 1 1.94241147
>
> 2 1.94250471
>
> 3 1.94246631
>
> 4 1.94248687
>
> 5 1.94229393
>
> 6 1.94231453
>
> 7 1.94227599
>
> 8 1.94236909
>
> 9 2.11493492
>
> 10 2.11493493
>
> 11 2.11493495
>
> 12 2.11493493
>
> ==================================
>
> Nr. of electrons (down): 24.00113738
>
> Atom populations (down)
>
> Atom Population
>
> 1 1.94255717
>
> 2 1.94265050
>
> 3 1.94261212
>
> 4 1.94263251
>
> 5 1.94275851
>
> 6 1.94277893
>
> 7 1.94274042
>
> 8 1.94283361
>
> 9 2.11489339
>
> 10 2.11489340
>
> 11 2.11489341
>
> 12 2.11489340
>
>
>
> here is part of my input file:
>
> ………….
>
> Filling = MethfesselPaxton {
>
> Temperature [Kelvin] = 300.0
>
> Order = 1
>
> }
>
> KPointsAndWeights = SupercellFolding {
>
> 12 0 0
>
> 0 12 0
>
> 0 0 1
>
> 0.5 0.5 0
>
> }
>
> SpinPolarisation = Colinear {
>
> UnpairedElectrons = 8.0
>
> RelaxTotalSpin = Yes
>
> InitialSpins = {
>
> AtomSpin = {
>
> Atoms = 1 2 3 4 5 6 7 8
>
> SpinPerAtom = +1.0
>
> }
>
> }
>
> }
>
> SpinConstants = {
>
> ShellResolvedSpin = Yes
>
> ………….
>
> Any help will be appreciated.
>
>
> Thank you
>
> Regards,
>
> Toufik
>
>
>
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>


--
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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