[Wien] born effective charge tensors

[Oleg Rubel]

The volume is preserved during the calculations of Born effective 
charges. Therefore, it is possible to use the "Shortcut" expression 
(also with i /= j)

Best regards
Oleg

-- 
Oleg Rubel (PhD, PEng)
Department of Materials Science and Engineering
McMaster University
JHE 359, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada
Email: rubelo at mcmaster.ca
Tel: +1-905-525-9140, ext. 24094
Web: http://olegrubel.mcmaster.ca

On 1/21/2020 8:41 AM, Wien2k User wrote:
> Dear wien2k users,
> 
> I want to calculate born effective charge tensors (martix) using 
> supercell method but in the following file in the page 23 it is 
> mentioned that if i = j (xx yy and zz) the volume is preserved
>   if if i / = j  the volume is preserved  or not ? despite that a0 b0 c0 
> are constant after the application of a displacement dr
> 
> https://www.bc.edu/content/dam/bc1/schools/mcas/physics/pdf/wien2k/Wannier%2BBerry-phase%2Bfold2Bloch.pdf 
> 
> 
> if not, how to calculate the other tensors in this case?