Yambo Community Forum

Dear all,

I'm currently performing some convergence studies for G0W0-PPA calculations for Si and LiF and noticed some weird behavior when setting XTermKind ="BG" and GTermKind = "BG". The attached plots show the convergence studies of the direct bandgap of Si and LiF for the parameter BndsRnXp, GbndRnge and NGsBlkXp. As shown on the wiki I converged NGsBlkXp and BndsRnXp simultaneously (W_conv) and GbndRnge in separate convergence study (G_conv). I'm wondering why the resulting direct bandgaps with and without the terminators differ so much in both cases and why the direct bandgaps don't seem to converge to the same value. Also the direct bandgap of LiF with XTermKind ="BG" and GTermKind = "BG" is much smaller than expected and round 1eV smaller than the direct bandgap calculated with the same settings and XTermKind ="none" and GTermKind = "none".

Best regards,
Max

Missing Plot

Dear Max,

we should have a close look at this to identify what's going wrong here. Probably some missing convergence in NGsBlkXp or maybe some non optimal position of the high energy pole.
My suggestion, in general, is to avoid to use XTermKind, as it is not always stable and memory intensive.
I suggest you to repeat your test using GTermKind only.

Best,
Daniele