[Wien] AFM supercell

[ROBERTO LUIS IGLESIAS PASTRANA]

Dear Peter

Thank you very much for your comments. I will try to set a clean initialization from scratch to avoid any typos or errors with symmetry. My case.inst file has the spins flipped in between consecutive atoms (i.e., 2nd is flipped against the 1st, 4th against the 3rd, etc., up to the 16 atoms). Is that a correct setting? I'm using the initial 16-atom supercell as the case.struct_supergroup file. Would that be correct?
An then, in order to set up an AFM calculation properly, which would the non-primitive translation be?

Best regards

Roberto

----- Mensaje original -----
De: Peter Blaha <pblaha at theochem.tuwien.ac.at>
Fecha: Viernes, Marzo 20, 2009 10:24 ombr
Asunto: Re: [Wien] AFM supercell

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> 
> Most likely you did some error in setting up the symmetry (crash in 
> dstart because euqivalent atoms not ok or
> sym.ops.are not ok,...) or in the arrangement of the magnetic 
> moments (flipping the spin of an "incorrect" atom).
> 
> Note: when you try a FM Cr calculation (bcc), the magnetism will 
> disappear (as you observed) since FM
> is not stable at all.
> 
> Also Cr has a spin density wave, so in some supercells it may 
> happen that you get different moments,....
> 
> ROBERTO LUIS IGLESIAS PASTRANA schrieb:
> > Dear all
> > 
> > I'm trying to run an AFM calculation in a 16 atom Cr supercell. I 
> want to have the Cr magnetic moment values 
> 
> for reference purposes, in order to compare to other systems of the 
> same size and later larger ones. The normal
> 
> bcc unit cell AFM calculation runs fine, following the procedures 
> outlined in the UG, section 4.5.4, and I get
> 
> the same magnetic moments for both Cr atoms in the cell but with 
> different signs.
> >  I set up a 16 atom supercell and then flip the spins of the Cr 
> atoms in consecutive pairs in case.inst. I 
> 
> also tried to flip just the second 8 atoms, unphysical as it may 
> be, and consequently there is a crash in dstart.
> 
> When I perform either a runsp_lapw or a runafm_lapw calculation I 
> always get zero, or close to zero magnetic
> 
>  moments in all sixteen Cr atoms, as if the system was in a 
> nonmagnetic state. The question is: What else do
> 
> I need to do in order to get final magnetic moments with the same 
> absolute values but with alternate different
> 
> signs, as for the bcc unit cell? Or am I writing nonsense?
> > I'm using WIEN2k_08.3 and running in 8 processors via k-point 
> parallelization.> 
> > Thanks in advance
> > 
> > Roberto
> > 
> > ---------------------------------------
> > Roberto Iglesias
> > Physics Department
> > University of Oviedo
> > Calvo Sotelo, s/n
> > 33007 Oviedo
> > SPAIN
> > Tel: +34985102898
> > Fax: +34985103324
> > email: roberto at uniovi.es
> > ---------------------------------------
> > 
> > --------------------------------------
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> -- 
> 
>                                       P.Blaha
> --------------------------------------------------------------------
> ------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
> Email: blaha at theochem.tuwien.ac.at    WWW: 
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