Yambo Community Forum

Hi Daniele,

Many thanks for this. Sorry for the delayed reply. For some reason I do not get notifications of the replies on my email.
I have run the BSE portion (construction of the kernel and solution of BSE) on top of calculations (QP calculation, static screening etc.) performed with the previous version of the code. Even though the new results look much better than the old ones, unfortunately, the lowest excitation energy is still negative! Is this because the QP and static screening calculations were run with the previous version? I am attaching the BSE output file and the list of excitation eigenvalues. It would be great if you could please let me know what you think.

Best regards,
Subhayan

Dear Subhayan,

it seems that there are still problems.
Your electronic structure now it seems reasonable as you do not have the metallic behaviour as before.
Anyway, in order to inspect carefully what is going on can you repeat your calculation from scratch (also using softer parameters). In the report you posted there are old databases (BSE and BSE diagonalized), even if they are discarded and recalculated. Please note you should avoid setting the XfnQPdb variable as you do not need to apply a scissor in the calculation of the screening. A possible problem is that you used an old screening calculated using a scissor that was not properly working.
Then besides the report and output can you also post the output of the quasiparticle GW calculations and absorption in order to have a look to the IP spectrum.

Best,
Daniele

Thanks Daniele,

I'll start working on this now.

Best regards,
Subhayan

A quick question. What do you mean by softer parameters here? Which parameters are you referring to?

Subhayan

Dear Subhayan,
it was just a simple suggestion to lower some parameters to make a quick check, even if not at convergence. Nothing relevant.

Daniele

Hi Daniele,

Please find attached the report and the output files from a fresh run performed with somewhat softer parameters. Please let me know what you think.

Best regards,
Subhayan

Dear Subhayan,
the QP energies seem that are correctly read now.
Anyway, can you also post the obtained spectrum (o*eps) in order to have a look at the independent particle response?

Best,
Daniele

Hi Daniele,

Thanks. The negative excitation energy is what I am concerned about
Please find attached the eps file.

Best regards,
Subhayan

Indeed,

from the IP spectrum I can see there is something odd, it appear transitions that should be forbidden.
I will do some checks,

Best,
Daniele

Hi Daniele,

Thanks for looking into this. Please let me know if you need any other files.

Best regards,
Subhayan