[Pw_forum] inequivalent atoms of the same type

W. YU yuwen_66 at yahoo.com
Wed Mar 14 04:26:57 CET 2007

Dear PW users,

I have a question concerning the "ntype" keyword:

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

Furthermore, in a phonon calculation, the phonon modes
are associated with different site symmetries. If the
two atoms in different symmetry sites were treated as
one kind, will the phonon modes be  different?  

I would appreciate it if anybody could explain this.

Wen Yu 

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