[Pw_forum] Get wrong symmtry

[yumin qian]

    thanks for all of you ,
   the problem have been solved by adding a parameter to the atomic_position
card.

ATOMIC_POSITIONS {crystal}
2008/11/10 yumin qian <yuminqian at gmail.com>

>    Thanks for your reply ,
>  But what is the problem is ?
>  I think there is nothing wrong to do with numerical accuracy , there may
> be something wrong with the code itself , could anybody give me a suggestion
>  to the solution of this problem?
>
> 2008/11/10 Michael Mehl <rcjhawk at gmail.com>
>
>  Axel Kohlmeyer wrote:
>> > On Sun, 9 Nov 2008, yumin qian wrote:
>>
>> > how about not having enough numerical accuracy
>> > for the numbers in the z-coordinate?
>> >
>> > axel.
>>
>> That would appear not to be the case.  The requirement for P4/nmm
>> symmetry is that z for the second atom in a pair be equal to -z (or 1-z)
>> for the first atom.  That's the case here.  Whatever the problem is,
>> it's not in the coordinates.
>>
>> (See http://cst-www.nrl.navy.mil/lattice/struk/AsCuSiZr.html)
>>
>> >
>>
>> > YQ> ATOMIC_POSITIONS
>> > YQ> La    0.2500000000    0.2500000000    0.1461000000
>> > YQ> La    0.7500000000    0.7500000000    0.8539000000
>> > YQ> O     0.7500000000    0.2500000000    0.0000000000
>> > YQ> O     0.2500000000    0.7500000000    0.0000000000
>> > YQ> Fe    0.7500000000    0.2500000000    0.5000000000
>> > YQ> Fe    0.2500000000    0.7500000000    0.5000000000
>> > YQ> As    0.2500000000    0.2500000000    0.6369000000
>> > YQ> As    0.7500000000    0.7500000000    0.3631000000
>>
>> --
>> Michael Mehl, Naval Research Laboratory, Washington DC.
>> Sabbatical Duke University through July 2009.
>>
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>
>
>
> --
> Sincerely Y. M. Qian
> Lab.of Condensed Matter Theory and Materials Computation
> Institute of Physics
> Chinese Academy of Sciences
> Tel:  + 8610 8264 9147
> E-Mail:yuminqian at gmail.com <E-Mail%3Ayuminqian at gmail.com>
> P.O.Box 603   Beijing 100190
> China
>
>


-- 
Sincerely Y. M. Qian
Lab.of Condensed Matter Theory and Materials Computation
Institute of Physics
Chinese Academy of Sciences
Tel:  + 8610 8264 9147
E-Mail:yuminqian at gmail.com <E-Mail%3Ayuminqian at gmail.com>
P.O.Box 603   Beijing 100190
China
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