[Wien] Slab convergence -- continuation

[Laurence Marks]

Make sure to look at the structures. I personally use atoms (Shape
software) and cryscon, or just xcrygen.

On Sun, Sep 26, 2010 at 1:50 PM, Lukasz Plucinski
<pluto at physics.ucdavis.edu> wrote:
>
>
> Dear Laurence,
>
> Thank you for the rapid comment.
>
>> The structure you sent is P4mm, with only one Fe. This about it, it is
>> not that hard.
>
> Right, but when I put Fe on the other side its still P4mm (sgroup does not
> discover other space group) , although it seems to me that there must be a
> difference. Au20 slab (without Fe) is also "discovered" as P4mm. I thought
> that maybe my z-axis positions were not accurate enough, so I checked this
> out today and retyped them with full (8 decimal digits) accuracy, and I
> still got P4mm for Fe1Au19Fe1.
>
> So I thought that maybe I do something wrong with my definition of the
> case.struct. Anyway, I will keep working on this.
>
> Regards,
> Lukasz
>
>
>
> On 9/26/2010 7:30 PM, Laurence Marks wrote:
>>
>> On Sun, Sep 26, 2010 at 11:57 AM, Lukasz Plucinski
>> <pluto at physics.ucdavis.edu>  wrote:
>>>
>>>  Dear Laurence, Prof. Blaha,
>>>
>>>
>>> So far I used default (spin up) for instgen. Do you mean that in
>>> case.inst
>>> file I should use "unpolarized" Au for most atoms in Fe1Au20 slab, and
>>> e.g.
>>> "up" Au only for 2-3 Au atoms near the surface ? (see below for example
>>> inputs for Au) Or maybe I should use "unpolarized" for all Au atoms ?
>>
>> Unpolarized for all Au
>>
>>> I understand case.inst only provide the starting configuration ? Is there
>>> a
>>> way to make some Au atoms permanently non-magnetic ?
>>
>> I don't think so.
>>
>>> In  the meantime I am having problems with getting inversion symmetry in
>>> my
>>> Fe/Au(001) slab. I created the Fe1Au19Fe1 slab with very precise
>>> positions.
>>> I also tried to force the equivalent positions for all but mid-slab Au
>>> atom... however, sgroup always finds the 99 (P4mm) group. I believe the
>>> concept of my slab is correct because I was able to reproduce the results
>>> of
>>> Li and Freeman JMMM 75, 201 (1988) for Fe1Au5 slab. I just paste this
>>> slab
>>> below, where theoretical Au bulk lattice constant of 4.11 A was used. I
>>> will
>>> keep working on this, but maybe there is some procedure I should use to
>>> get
>>> the inversion symmetry (to get rid of the complex version of the
>>> program).
>>
>> The structure you sent is P4mm, with only one Fe. This about it, it is
>> not that hard.
>>>
>>> Regards,
>>> Lukasz
>
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-- 
Laurence Marks
Department of Materials Science and Engineering
MSE Rm 2036 Cook Hall
2220 N Campus Drive
Northwestern University
Evanston, IL 60208, USA
Tel: (847) 491-3996 Fax: (847) 491-7820
email: L-marks at northwestern dot edu
Web: www.numis.northwestern.edu
Chair, Commission on Electron Crystallography of IUCR
www.numis.northwestern.edu/
Electron crystallography is the branch of science that uses electron
scattering and imaging to study the structure of matter.