[Wien] structure confusion ?

[Peter Blaha]

Consider the most simple structure, namely a primitive cubic one with just one
atom at the origin. When you view thus structure, you will of course see
8 atoms (on all corners of the cube).
Atoms at the surface of the unit cell do not count fully, as they may belong to
2 (faces), 4 (edges) or even 8 (corners) other unit cells.

Am 30.04.2013 06:22, schrieb Zaid:
> Respected Community
>
> I have a little confusion in understanding the spinel structure. I am attaching a perfect MgAl2O4 spinel structure. Why this structure shows more than 8 Mg (Yellow in
> colour) elements ? There should be 8 Mg, 16 Al and 32 O atoms that adds up to give 56 atoms. I also see more no of atoms in Xcrysden.
>
> Best wishes
> Zaid
>
>
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-- 
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Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pblaha at theochem.tuwien.ac.at
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