Applying self-consistancy on the eigen values with wave vector dependent scissor to obtain effective mass

[pravin_karna]

Hello all!
I am Pravin Karna.
I am quite new to YAMBO code.
I was trying to mimic a GW correction in a research article where they have corrected the band gap using GW correction. However, they have gone beyond G0W0 correction by applying self consistency on the eigen values with wave vector dependent scissor to obtain the effective masses. Can you guys please tell me how can we achieve this.
Also, how can we apply polarizability cutoff. Is it changing the value in NGsBlkXp?

Lastly is there a way to find what is the optimum number of bands and k points on which we can apply the GW correction. Right now in my input file, the
QPkrange
1|286|1|750|

which I believe is too high for calculation.

Thank you in advance for your time

[Daniele Varsano]

Dear Pravin,

please sign your post with your name and affiliation. This is a *rule* of the forum, you can do once for all by filling your signature in the user profile.

1) K-depend scissor is governed by the keyword:

Code: Select all

% GfnQP_E
 0.000000 | 1.000000 | 1.000000 |        # [EXTQP Xd] E parameters  (c/v) eV|adim|adim
%

The first number provides a global scissor while the 2nd and 3rd filed are stretching parameter for conduction and valence respectively. You can add this keyword in the band interpolation calculated with ypp. See e.g. Step 3 of this tutorial:
https://www.yambo-code.eu/wiki/index.ph ... rial:_h-BN


2) NGsBlkXp, yes it governs the cutoff in the dielectric matrix dimension when using the plasmon-pole approximation.

3) That's up to you. It depends on what do you want to look at. By default, it includes all bands and k points, but in general one is interested to very few bands around the gap/Fermi energy. For convergence tests, it is usually enough to calculate the direct/indirect gap, ie one or few k points and two bands.

At this page, you can find tutorials for the Yambo code usage.

Best,

Daniele

[claudio]

You can also have a look to the Tutorial on self-consistent GW on the eigenvalues only:

https://www.yambo-code.eu/wiki/index.ph ... alues_only

best
Claudio