EPW velocity Definition between QE-6.0 and QE-7.0

[Vahid]

Dear EPW Community,

In the QE-6.0 version of EPW, dipole velocity was defined as

Code: Select all

vkk(:,ibnd) = 2.0 * REAL (dmef (:, ibndmin-1+ibnd,ibndmin-1+ibnd, ikk))

In the latest version, the factor 2 is missing. Are both correct?

Thank you,
Vahid

Vahid Askarpour
Dalhousie University
Halifax, Canada

[Vahid]

Since there has been no response, is it safe to assume that one of those versions is incorrect?

Thanks,
Vahid

[hlee]

Dear Vahid Askarpour:

Please use the recent versions of EPW.

Since EPW v5.4, the expression of dme has changed to make it include the non-local part of pseudopotential and along with this change, the factor of 2 have been removed.

PS) At this point, I don't remember whether the factor of two should be removed in the expression of dme in the previous versions.

Sincerely,

H. Lee

[Vahid]

Dear H. Lee,

Thank you for your response. Upto qe-6.7MAX, the factor 2 is included in the velocity expression. Only 6.8 and 7.0 have removed the 2.

Thanks,
Vahid