G0W0@PBE or G0W0@HSE06

[emarinho]

Dear all,

I am performing G0W0 calculations for a novel 2D material. So far, there are no experimental results on the electronic properties of this material. Within the DFT-PBE level, its band gap is 0.05 eV, which increases to 1.10 eV by applying HSE06 functional. When I computed the quasiparticle correction at the G0W0 level, I obtained a quasiparticle gap of ~0.6 eV, smaller than the one we get with DFT-HSE. In this case, should I perform G0W0@HSE or the gap result at G0W0@PBE is reliable, considering that the DFT-PBE band gap is tiny?

[Daniele Varsano]

Dear Enesio,

there is not a unique answer to your question. Not having an experimental counterpart, it is not easy to assess which method is performing better. Please note that G0W0@HSE has some issues in Yambo due to a technical problem (different way to treat the divergences between QE and Yambo so at the moment it has been disabled.

In order to assess the starting point issue, you can for instance try to do an eigenvalue only self-consistent calculation, having in mind that, depending on the system, it can overestimate the band-gap.

Here is a tutorial for this kind of calculation:
https://www.yambo-code.eu/wiki/index.ph ... alues_only

Best,
Daniele