[Wien] Slab convergence -- continuation

[Lukasz Plucinski]

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