How to set the number of NLBands in yambo_nl calculation?

[Davy-Hou]

Dear developers,

I use yambo_nl -u to generate a yambo.in file for nonlinear optical calculation. How can I set the number of NLBands?

In the example of AlAs, there are 4 orbitals occupied by electrons and 11 empty orbitals. In the yambo.in file, the NLBands values are 3 and 6, respectively. I am not sure how to set the band range values? Could you give me some hints? Thank you very much!


Best regards,
Davy Hou

[claudio]

Dear Davy Hou

in principle you should include bands close to the gap,
for example in the AlAs the gap is between the bands 4 and 5,
and therefore we include 2 valence and 2 conductions, namely from band 3 to 6.

You should test that this band range is enough to converge your non-linear response
in the energy range you are interested in.
For example you can repeat calculations with bands range 2-6, 1-6, 2-7, 2-8 etc... and see
if the result changes.
If it does not change it means that your results are converged respect to the bands range.

best
Claudio

[Davy-Hou]

Dear Dr. Claudio Attaccalite,

Thank you so much for your kind help. I will do the tests according to your advice.

Best regards,
Davy Hou