Yambo Community Forum

Dear YAMBO developers and users,

I'm currently trying to run a G0W0 calculation exploiting the double grid feature. I performed an nscf run on a dense grid (32x32x1) and in the coarse grid (9x9x1) SAVE I successfully created the ndb.DoubleGrid database. However, when I run the G0W0 calculation on the coarse grid, even though in the report and logfile I notice that YAMBO uses the fine grid I get a gap result that is extremely close (just 1 or 2 meV away) to the straightforward coarse grid calculation (without double grid).
What am I missing? I would expect a bigger impact of the double grid on the GW calculation. I also tried with a finer coarse grid (14x14x1) but the outcome did not change, the double-grid result is very close to the coarse one.
I'm attaching the input, report and logfiles of my calculations.
Thank you very much for your help!
Best,


Michele

Dear Michele

I think this is due to the no correct treatment of the q=0 term,
that unfortunately the double-grid cannot solve.
You may have a look here:

How dielectric screening in two-dimensional crystals affects the convergence of excited-state calculations: Monolayer MoS2
Falco Hüser, Thomas Olsen, and Kristian S. Thygesen
Phys. Rev. B 88, 245309
https://core.ac.uk/download/pdf/192327286.pdf

maybe Daniele will add more comments on this point.

best
Claudio

Hi Michele,
indeed we have very decently developed a new technique to accelerate GW convergence for 2D materials. This development it is not yet merged in the official release, but it will merged soon.

Best,
Daniele

Dear Claudio and Daniele,

thank you very much for your answers! I'm looking forward to the new release then!
Best,


Michele