[Wien] Symmetry in SG Fm3c

Peter Blaha pblaha at zeus.theochem.tuwien.ac.at
Mon Apr 4 17:45:08 CEST 2005


> in the cubic spacegroup Fm3c there seem to be some
> inconsistencies in the symmetry-operations (SO)
> seen by comparison of the ones generated 
> with those listed in the International Tables (IT)

No there is no error in the symmetry operations. For a fcc cell you can 
always add/subtract any combination/permutation of (1/2,1/2,0) to all 
operations or positions and don't get anything new.

In most of our programs these translations are taken into account in 
rotdef.f and testing of these shifts is done.

Unfortunately, for aim this has not been done so far. Most likely it is 
analogous to what has been done in other rotdef.f versions, although the 
rotdef of aim is different !! than others.
So "here is the bug".

So at the moment I recommend as a quick fix either to change the symmetry 
operations by hand (as you have almost done), or change the position of 
the equivalent atoms (not the first one, but the others)



                                      P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
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