[Wien] regarding case.struct generation

[Peter Blaha]

The virtual crystal approximation will not work well in a case with 
active d-electron elements.

You have to use supercells.

Am 08.02.2016 um 14:32 schrieb Farshad Nejadsattari:
> Dear Professor Blaha, Wien2k community and experts,
>
>     I am working on the compound Al72Ni9Fe19. This system crystallizes
> in the space group P63/mmc (No. 194). Two of the Wyckoff sites are
> partially occupied by Fe and Ni atoms, I would like to know how to
> construct the master input file, (case.struct) for this system since
> both atoms occupy the same Wyckoff sites but with different proportions.
> I have looked through the mailing list and have not found anything
> particular regarding this type of problem. The atomic positions are
> given below:
>
> *_Atom_**_Wyckoff Site_ _ (x,y,z)_*
> *_
> _*
> Al(1)                                                   2/a/
>                                                 (0,0,0)
> Al(2)                                                   6/h/
>                                                 (0.4647,0.9294,0.25)
> Al(3)                                                   12/k
> /(0.1935,0.3870,0.9392)
> 0.6786Fe(1)+0.3114Ni(1)                       2/d/
>                                       (1/3,2/3,3/4)
> 0.6786Fe(2)+0.3114Ni(2)                       6/h/
>                                       (0.1256,0.2512,0.25)
>
>       As seen above, the iron and nickel atoms occupy the Wyckoff sites
> at an approximate 2/1 (Fe/Ni) ratio. Your assistance towards
> constructing the case.struct file for this compound is truly appreciated.
>
> With regards,
>
> Farshad Nejadsattari,
> PhD candidate in condensed matter physics,
> University of Ottawa, Canada
>
>
>
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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