[Wien] Help on AFM Structure

Peter Blaha pblaha at theochem.tuwien.ac.at
Mon Jan 20 09:31:33 CET 2014


This is the wrong strategy. I expected that it is C-centered.

How many Fe positions do you have in CXZ ?
Try to play with the magnetic configurations in this symmetry first.

Eventually you could give up the C-centering and make the formerly 
centered-atoms antiferromagnetic to the other ones.

Try to visualize the magnetic structures as I told you before. If the 
magnetism is not know from experiment, you have to make "computer 
experiments", but start with the MOST simple possibilities and then 
gradually test more complicated ones.

On 01/20/2014 09:24 AM, Chinedu Ekuma wrote:
> Dear Peter,
> The original structure was a CXZ structure but for the AFM calculations,
> I made all the multiplicity to be 1 and then after that, running x
> sgroup lead to the reduction in the symmetry.
>
> *Ekuma
> *
> /
> /
> ////
>
>
> On Monday, January 20, 2014 3:19 AM, Peter Blaha
> <pblaha at theochem.tuwien.ac.at> wrote:
>  From where did you get the structure ?? It is really P1 ??
>
> Did you remove the  the 1,2,3,.. from Fe1, Fe2,..Ga1,Ga2,...  ???
>
> Maybe there is some rounding error in the positions which prevents
> higher symmetry ??
>
> On 01/20/2014 08:55 AM, Chinedu Ekuma wrote:
>  > Dear Peter,
>  > The structure is the default structure as obtained from running x sgroup.
>  >
>  > Best.
>  >
>  > *C.  Ekuma*
>  > /
>  > /
>  > ////
>  >
>  >
>  > On Monday, January 20, 2014 2:27 AM, Peter Blaha
>  > <pblaha at theochem.tuwien.ac.at <mailto:pblaha at theochem.tuwien.ac.at>>
> wrote:
>  > Is there a reason why you did setup this case in P1 symmetry ???
>  >
>  > You seem to have  Fe18 Ga24, which is the same as Fe3 Ga4
>  >
>  > What happens when you remove all "labels"  (1,2,3,... 24) of the atoms ?
>  > Wien2k will then find out which atoms are equivalent and which are
>  > different by symmetry.
>  > Maybe this is even a C-centered monoclinic structure ?
>  >
>  > Anyway, when you have a structure which has only a "few" (2-4)
>  > nonequivalent Fe positions, then it makes sense to play with magnetic
>  > order and compare total energies.
>  >
>  > You would start in different directories and BEFORE init_lapw run
>  > instgen_lapw -ask and specify the desired magnetic order by chosing up
>  > or dn for each Fe site (and nm for Ga).
>  >
>  > For visualisation you may create a struct file where you rename your
>  > atoms to Co, Ni,...., so that you can distinguish them in xcrysden and
>  > then you can see how to arrange the magnetic moments to get them in a
>  > specific order.
>  >
>  >
>  > On 01/19/2014 01:41 AM, Chinedu Ekuma wrote:
>  >  > Dear All,
>  >  > I am trying to construct a collinear AFM structure from the attached
>  >  > file. Please, any help will be greatly appreciated.
>  >  >
>  >  >  Thanks.
>  >  > *C.  Ekuma*
>  >
>  >  >
>  >  >
>  >  >
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>  >                                        P.Blaha
>  >
> --------------------------------------------------------------------------
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>                                        P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300            FAX: +43-1-58801-165982
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                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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