[Pw_forum] about born effective charge tensors

[Resul Eryigit]

> I'm not sure about whether the born effective charge tensor should be 
> symmetric in crystals. Does it dependent on the structural symmetry of 
> crystal itself ?
>

the exact form of the Born effective charge tensor is determined by the site 
symmetry of the atom..if you have site symmetry information, you can 
check,for example, A. S. Nowick's Crystal Properties via Group Theory  to 
see if the form of the tensor you have calculated is whats supposed to be on 
the symmetry grounds.