[Pw_forum] inequivalent atoms of the same type

[Paolo Giannozzi]

On Mar 14, 2007, at 4:26 , W. YU wrote:

> In a non-magnetic case, if I have the same kind
> (chemically) of atoms which occupy different symmetry
> sites, say "4c" and "4e",and I made them belong to the
> same "type", how will the code find the symmetry for
> these two inequivalent kinds of atoms.

the code works on the complete cell, not on the subset
of inequivalent atoms, and finds the symmetry by trying
a set of candidate symmetry operations.

> If it cannot differentiate between these two symmetry
> sites, will this has some effect on the results?

no. The code knows which atom transform into which
under which symmetry operation. Atoms belonging to
different symmetry sites will never transform into each
other.

Paolo
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Paolo Giannozzi, Democritos and University of Udine, Italy