Analysing elph matrix elements

Deals with issues related to computation of optical spectra in reciprocal space: RPA, TDDFT, local field effects.

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sitangshu
Posts: 175
Joined: Thu Jan 05, 2017 8:08 am

Analysing elph matrix elements

Post by sitangshu » Sat Mar 11, 2023 10:16 am

Dear Yambo guys,

There are some of my queries regarding elph data:

1. Is

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Sc|E [eV] 
appearing in elph o-qp-0K.qp file is self energy including elph corrections? If so, how can I get electron-acoustic & electron-optical phonon self energies?

2. Is

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Re(G) [eVm1]
appearing in elph o-sf-0K.G_Sc_band_* file gives the Re[spectral function]? The header seems to be Re[Green] :roll:

3. I have now the SAVE folder where ndb.elph.gkkp* elph matrix element files are there together with the ndb.PH_Double_Grid file. How can I get information about the electron-acoustic and electron-optical phonon deformation potentials?


Regards,
Sitangshu
Sitangshu Bhattacharya
Indian Institute of Information Technology-Allahabad
India
Web-page: http://profile.iiita.ac.in/sitangshu/
Institute: http://www.iiita.ac.in/

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claudio
Posts: 448
Joined: Tue Mar 31, 2009 11:33 pm
Contact:

Re: Analysing elph matrix elements

Post by claudio » Mon Mar 13, 2023 10:54 am

Dear Sitangshu

answers to your questions:
1) yes it is the electron-phonon self-energy

if you want self-energy only for the acustic or for the optical phonons,
you just select them in the input and repeat the calculation.
For example for the autistic you can set:

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% ElPhModes
  1 |  3 |                           # [ELPH] Phonon modes included
%
and for the optical

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% ElPhModes
  4 |  xx |                           # [ELPH] Phonon modes included
%
where xx is your last phonon mode.

2) I have to check

3) other people will reply to this question
Claudio Attaccalite
[CNRS/ Aix-Marseille Université/ CINaM laborarory / TSN department
Campus de Luminy – Case 913
13288 MARSEILLE Cedex 09
web site: http://www.attaccalite.com

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palful
Posts: 56
Joined: Tue Jan 26, 2016 11:23 am
Location: Modena and Milan

Re: Analysing elph matrix elements

Post by palful » Mon Mar 13, 2023 11:24 am

Hi Sitangshu,

2) This should indeed be the real part of the quasiparticle electron Green's function after electron-phonon effects are included. Its imaginary part (Im[G]) is the spectral function instead. But let's wait for Claudio to confirm. Getting the frequency-dependent, complex Green's function or just the linearised quasiparticle solution (i.e., only band shifts and broadenings) depends on the solver option in the input.

3) You could visualize the k-space or q-space maps of the electron-phonon interaction potential (the 'g' matrix elements) using yambopy. In particular you can check this part of the yambopy tutorial. The relevant scripts are in the yambopy repository at tutorial/databases_yambopy.

Cheers,
Fulvio
Dr. Fulvio Paleari
S3-CNR Institute of Nanoscience and MaX Center
Modena, Italy

sitangshu
Posts: 175
Joined: Thu Jan 05, 2017 8:08 am

Re: Analysing elph matrix elements

Post by sitangshu » Tue Mar 14, 2023 11:57 am

Hello Professor Claudio and Fulvio,

Many thanks for your answers.
I am trying to compute the mode dependent elph scattering rates, which are proportional to the -Im[elph self-energies]. If I know this somehow, then I can also find out other transport coefficients like mobility etc. The code seems to write only the Real part

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Sc|E [eV] 
. Is there anyway to get also the Im[elph self-energies]?

Regards
Sitangshu
Sitangshu Bhattacharya
Indian Institute of Information Technology-Allahabad
India
Web-page: http://profile.iiita.ac.in/sitangshu/
Institute: http://www.iiita.ac.in/

sitangshu
Posts: 175
Joined: Thu Jan 05, 2017 8:08 am

Re: Analysing elph matrix elements

Post by sitangshu » Fri Mar 17, 2023 5:47 pm

Apparently, I could not get around of this super bug in the elph spectral function output. This E-152 seems to be always coming. Is this a problem with this version?

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#Version 5.1.0 Revision 21422 Hash (prev commit) fde6e2a07           
#                        Branch is                                    
#               MPI+SLEPC+HDF5_MPI_IO Build                           
#                http://www.yambo-code.org   
#
#
# Spectral function at this point integrates to:  0.4082163E-152
#
#
#    Energy [eV]        Re(G) [eVm1]       Im(G) [eVm1]       Re(S_tot) [eV]     Im(S_c) [eV]
#
       -1.890873          -0.341685           0.1670E-155       -0.073324           0.1430E-154
       -1.878849          -0.343094           0.1684E-155       -0.073324           0.1430E-154
I have attached the report file and the sf output also. The ZPR gap seems to be reasonable.
I am although aware of Professor Attacallite's response:

Code: Select all

Dear Sitangshu

I tried to reproduce your error with the last version of the GPL

https://github.com/yambo-code

but I did not get any error.
Please try again with the last version, and in any case use the same version
of Yambo for the BSE and the interpolation

best
Claudio
An advice (perhaps the Yambo version with a revision number and branch number) will be be greatly admired.

Regards
Sitangshu
Sitangshu Bhattacharya
Indian Institute of Information Technology-Allahabad
India
Web-page: http://profile.iiita.ac.in/sitangshu/
Institute: http://www.iiita.ac.in/

sitangshu
Posts: 175
Joined: Thu Jan 05, 2017 8:08 am

Re: Analysing elph matrix elements

Post by sitangshu » Fri Mar 17, 2023 5:49 pm

File is attached.
Regards
You do not have the required permissions to view the files attached to this post.
Sitangshu Bhattacharya
Indian Institute of Information Technology-Allahabad
India
Web-page: http://profile.iiita.ac.in/sitangshu/
Institute: http://www.iiita.ac.in/

sitangshu
Posts: 175
Joined: Thu Jan 05, 2017 8:08 am

Re: Analysing elph matrix elements

Post by sitangshu » Mon Mar 20, 2023 4:12 pm

Any update?

Regards,
Sitangshu
Sitangshu Bhattacharya
Indian Institute of Information Technology-Allahabad
India
Web-page: http://profile.iiita.ac.in/sitangshu/
Institute: http://www.iiita.ac.in/

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