Yambo Community Forum

Dear developers:
For low-dimensonal systems, if we want to obtain the higher energy region (far from Fermi level) band structures which originate from free electron states, these bands will down-shift(the two black paralell ones in blue rectangle in attachment) compared to others not from free states owing to the interaction between neighbouring unit cells. My point is: shall we have any another choice except for increasing our vacuum thickness for obtaining these free electron bands?
Thanks!

Shudong

Dear Shudong,
I would say that the only way is to increase the vacuum, even if I'm not sure I exactly understood what you observed.
What are exactly the black and red point in the plot? Are these LDA and GW energies?
Cheers,

Daniele

Daniele Varsano wrote:Dear Shudong,
I would say that the only way is to increase the vacuum, even if I'm not sure I exactly understood what you observed.
What are exactly the black and red point in the plot? Are these LDA and GW energies?
Cheers,

Daniele

Dear Daniele,
All rae the GW bands with different two PPA value. In LDA structure, the two paralell band in renctangle upshift.I give another two plot of gw and lda bands.
Shudong

Dear Shudong,
you can try to see the effect of the cell size on that bands, even if I do not think that the GW correction will be strongly affected. Anyway, if you are interested in optics, hopefully that bands should not affect the results for bound excitations.

Cheers,

Daniele