[Pw_forum] Get wrong symmtry

[Michael Mehl]

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.