[Pw_forum] further: born charges in rhombohedral unit cell.

[sonu kumar]

 Respected Prof. Stefano de Gironcoli and QE users,

>Are the symmetry operations determined in the two systems the same ?

Yes.

>because there is a symmetry reason.
>like a mirror plane or something ...

 Na(H)  and F have  D3d , C3v  site sym resp.

>If your symmetry allows the born effective charge to be non zero they
>will, much or little depending on the details of the system.

NaHF2 is mainly ionic than CuAlO2, so one may  expect to have differences
in born-effective charges.

Thank you very much.

with regards,
Sonu
IITD
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