Yambo Community Forum

Dear Developers,

I used the BSE-slepc solver for metallic systems. After BSE calculation, I apply "ypp -e s 1".
I have attached the logic, report, and outcome files for my calculation. I couldn't figure out why the exciton sortings are uneven. Can excitons take place in negative energy levels? Or did I perform the BSE calculation wrong?

Best regards,
Zafer

Dear Zafer,
I suspect that the problem here is due to the fact that you have a metallic system but the metallic character in the screening for q=0 (inraband contribution, Drude term) is not taken into account. The problem can be mitigated by considering larger and larger k point grids.

Anyway, are you sure that you need BSE for the absorption of a metal? Usually, the IP approximation is a good one for metals.

We are now working to include metallic terms in the code, in particular for GW, and hopefully it will be ready soon.
Best,
Daniele