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### Re: full GW+BSE calculation

Posted: Mon Apr 11, 2016 4:14 pm
Dear Khaled,

1) When you solve the BSE, the meaningful part of the exciton energy is the real part. If you are interested in exciton lifetime you need to do a model for it first.
2) If you want to extract the transition dipole matrix you can write them either looking into ./src/bse/K_diag_compute_epsilon.F, when the epsilon is built after the diagonalization of the dielectric matrix.
Otherwise with the postprocessing ypp, when excitons are sorted out (have a look in ./ypp/exciton_sort_and_report.F), the BS_R are read, normalized and printed out.

Best,

Daniele

### Re: full GW+BSE calculation

Posted: Wed Apr 13, 2016 2:01 pm
Dear Dr. Daniele Varsano,

Thanks a lot Dr. Daniele for your great help. I was able to extract the transition dipole matrix, but I am not sure a bout the units of the transition dipole matrix $| \sum_{vck} \langle vq-k | e^{-iqr} | ck \rangle A_{\lambda} |^{2}$
because I extracted this term alone (even I couldn't figure out if you used the electric dipole approimation for this term or not). Please, Can you help me for getting this information. Thank you in advance.

Best regards,

Khaled.

### Re: full GW+BSE calculation

Posted: Fri Apr 15, 2016 3:36 pm
Dear Khaled,
the internal unit in the code is the atomic unit (bohr for length, Hartree for energy etc..).
The electric dipole approximation it is used for the q=0 term.

Best,

Daniele

### Re: full GW+BSE calculation

Posted: Thu Aug 11, 2016 5:23 pm
What is exactly the unit of the matrix elements ?

A transition dipole has SI units of Coulomb.meters, so here, should it be electron charge.bohr ?

### Re: full GW+BSE calculation

Posted: Tue Aug 16, 2016 9:41 am
Dear Thierry,
yes, it should be as you wrote.

Daniele