SCF potential in Born effective Charge

[simba2828]

Dear developers and Experts,

Is it possible to collect/extract the dV_scf/du term as shown in the picture attached using QE/EPW? This is a formula for calculating the Born effective charge. I am sure this data (dV_scf) is stored somewhere (most probably in the binary files *.dvscf). If someone knows how can I collect this data, if there is any utility in EPW or QE please let me know. I would really appreciate the help.

Thank you very much.

Sincerely,
Shubham

[sponce]

Dear Shubham,

The .dvscf file contains part of the dV^KS/dU. One then have to add the Ewald terms and then take the sandwich with the wavefunctions.

The whole term <u|dV/du|u> is contained in the .epb files.

Note that in EPW we have it for <k+q|dV/du|k> so you will need to look at q=\Gamma only for this one.

Best wishes,
Samuel