Yambo Community Forum

Dear All,

Does the fourth column in the file of "o.eps_q1_haydock_bse" include the so-called local field effects?
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# E/ev[1] eps /Im[2] eps /Re[3] eps0/Im[4] eps0/Re[5] eps`/Im[6] eps`/Re[7]

0.000 0.6630E-3 1.413 0.4392E-3 1.337 0.6630E-3 1.413
0.2002E-1 0.6708E-3 1.414 0.4438E-3 1.337 0.6708E-3 1.414
0.4004E-1 0.6786E-3 1.415 0.4484E-3 1.338 0.6786E-3 1.415
0.6006E-1 0.6866E-3 1.417 0.4531E-3 1.339 0.6866E-3 1.417
0.8008E-1 0.6946E-3 1.418 0.4578E-3 1.340 0.6946E-3 1.418
... ...
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If not, how can I obtain a GW absorption spectrum including the local field effects? Can I use the "KfnQPdb= "E < ./SAVE/ndb.QP"" in the "yambo -o c -V qp" calculation?

Thank you very much!

Dear WEI Wei

you can obtain a GW absorption spectrum including the local field effects doing

yambo -o c -V qp

and then setting

XfnQPdb="E < ./SAVE/ndb.QP"

Cla

Dear Claudio,

Thank you very much for your reply!
So, the difference between eps0/Im[4] from o.eps_q1_haydock_bse and the yambo -o c -V qp is that the former does NOT include the LFE?
If I use yambo -o c -V qp, how to set the variables like XfnQP_W, XfnQP_Z?

Thanks!

Hallo

The eps0 is the independent particle one, so yes no many-body effects are there (e.g. no LF or excitonic effects)

Best
m

If you want to include Qp energy corrections, just set the XfnQP_E variable.
Cheers,
Daniele

Dear Daniele & Myrta,

Thank you very much!
I know I can do it by setting the XfnQP_E, but it is OK for a system with an indirect band gap?
In addition, I want to know that can I use the "XfnQPdb="E < ./SAVE/ndb.QP"" in the input file without setting the other relative variables?

Thanks!

Dear Wei,

I know I can do it by setting the XfnQP_E, but it is OK for a system with an indirect band gap?

Here you are reading the QP corrections that you should have calculated in advance. Using the variable with that
syntax it is not a scissor!

In addition, I want to know that can I use the "XfnQPdb="E < ./SAVE/ndb.QP"" in the input file without setting the other relative variables?

Yes you can, if you are interested in the energy corrections, this is the variable to use.

Cheers,
Daniele

Dear Daniele,

OK, I see.
Thank you so much for your patience!