[QE-users] Units, and real/imaginary parts of matrix elements of momentum operator in band.x

[weiyd at hit.edu.cn]

Dear Developers and Users:

  I am calculating the magnitude of matrix elements of momentum operator p with band.x, trying to calculate the optical properties of the materials. but I am not sure about the units of momentum operator in p_avg.dat, is the unit exactly the atomic unit: 1.99285191410(30)×10−24 kg·m·s−1 ?

  Another question: from "write_p_avg.f90" code, the output "p_avg.dat" writes the square of absolute value of operator. If I change the output script: 

(abs(matp(ibnd-nbnd_occ,jbnd,ipol))**2 into 

(real(matp(ibnd-nbnd_occ,jbnd,ipol)) or (aimag(matp(ibnd-nbnd_occ,jbnd,ipol))

Is that method correct to get the real and imaginary part of matrix elements of momentum operator?




Thanks for your time








======================================
Yadong Wei,
Department of Physics,
Harbin Institute of Techonology,
Harbin, China
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