GW QPband

[WEIW]

Dear all,

There was no error when I performed gw calculation, but I wondered why the corrected energy band would appear in a relatively "chaotic" state. What are the reasons for this?

I have attach the relevant results below. Figure 1/2 shows the band structure calculated with/without GW correction respectively.

Thanks in advance.
Best,
Liu

[claudio]

Dear Liu

probably it is not an error of the GW calculations but a problem in the interpolation.
When two bands cross each other in the GW, the interpolation could fail, because it is not able
to recognize the crossing.
My advice is to plot directly the points that you obtain from the GW without interpolation,
you should be able to recognize the bands and their path without strange behaviours.

best
Claudio

[WEIW]

Dear Claudio,

Thanks for your advise!

I'm not sure how to implement "plot directly without interpolation". I would appreciate it if you could explain it in detail. Thank you very much!

Best,
Liu

[Daniele Varsano]

Dear Liu,

you can plot the calculated QP energy that are found both in the o.qp* file and in the report file.

Best,
Daniele

[nilesh12]

Dear all,
I am working on 2D heterostructures. For one of the stable stacking, I am getting GW band gap is smaller than PBE band gap. For me, it seems very unusual. This is when I used PPA approach. For the same stacking with COHSEX approach, I got the normal trend GW > PBE.
Please help me regarding this, I am not able to understand the physics behind it.

Thank you

[Daniele Varsano]

Dear Nilesh,

in order to help you, you need to provide more details (what test you did, an example of the report file etc..) otherwise it is not possible to understand your problem.

Best,

Daniele