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How to get the GW wavefunction

Posted: Tue Mar 02, 2021 3:42 am
by jasonhan0710
Dear all,

I want to read the many-body wave functions and charge density. Specifically, I want to get the quasiparticle corrected wave function and substitute the wave function files in the 'prefix.save' directory. Which file should I read and how to transfer it into Quantum-ESPRESSO format?

Best regards,
Jason

Re: How to get the GW wavefunction

Posted: Tue Mar 02, 2021 9:24 am
by Daniele Varsano
Dear Jason,
in order to have GW wavefunction a sort of self-consistency is needed, at the moment yambo calculate G0W0 or eigenvalue self-consistent GW which is a diagonal approximation so the wfs are not changed. There is the possibility to perform a coshex self-consistency, but it is not properly tested so it is not distributed with the GPL release.
Best,
Daniele

Re: How to get the GW wavefunction

Posted: Tue Mar 09, 2021 2:59 am
by jasonhan0710
Dear Daniele,

Thanks for your reply.
in order to have GW wavefunction a sort of self-consistency is needed
What kind of self-consistency do we need? Can we just get the self-energy with Yambo and put it into the SCF calculation, just like a DFT+U calculation? Do you think it's a reasonable approximation?
There is the possibility to perform a coshex self-consistency
If possible, would you please send me a copy of this version?

Also, I have another question. What is the output in "ndb.QP" file? How to read it and get the quasiparticle energy?

Best regards,
Jason

Re: How to get the GW wavefunction

Posted: Tue Mar 09, 2021 9:04 am
by Daniele Varsano
Daer Jason,
What kind of self-consistency do we need? Can we just get the self-energy with Yambo and put it into the SCF calculation, just like a DFT+U calculation? Do you think it's a reasonable approximation?
Self energy are non-local object and QE is not meant to do that. If you want to perform a quasi-particle self consistent calculation you may have a look to the works of of Mark van Schilfgaarde: M van Schilfgaarde, T Kotani, S Faleev Physical review letters 96 (22), 226402

this is implemented in the quest all code: https://www.questaal.org/get/

Anyway, are you sure you need to perform quasi-particle self consistent calculations?
If possible, would you please send me a copy of this version?
This is a develop version and it s not yet ready to be distributed.
Also, I have another question. What is the output in "ndb.QP" file? How to read it and get the quasiparticle energy?
This is the yambo database in netcdf format containing the quasi-particle corrections. QP energy can be read both in the report and in the output o.qp of the calculation.

Best,
Daniele