Interpolation neighbours

[davood]

Hi
I calculated the GW level, and obtained band structure (GW and DFT),I ploted band of GW with GfnQP_N=1 and GfnQP_N=50 (band of DFT with GfnQP_N=1).
1-Is it correct to use GfnQP_N=50 for band structure?
2-If it is true,Should I use it at ‌BSE level with GfnQP_N=50?

Best Regards

[Daniele Varsano]

Dear Davood,
GfnQP_N it is used for interpolation of QP correction to be inserted in the Green function, so essentially in ypp is used for bands and dos in order to have values for more point than ones you explicitly calculated. Anyway using ypp and giving a Path (% BKpts) , ypp will interpolate along that path: you can have a look to this post post in case you have noise if you have a non 3D k-point sampling.Essentially you do not need to use the GfnQP_N variable.

When including the correction in the BSE, you need to include them in the kernel so the variable to use are KfnQPdb (if you use qp energy previously calculated contained in the ndb.QP) and , KfnQP_N (if the calculated QP are less than the bands used in the BSE so you want to consider qp corrections for the missing bands by interpolation), alternatively you can use KfnQP_E if you can use a scissor operator approximation.

Best,

Daniele