Electron-Phonon effects

[amolina]

Dear Martin,

I am not sure what can be the reason of this error. It seems a problem with the file s.dbph_000003. Maybe you can repeat the calculation for that file and try again (remove the ndb.gkkp* files before doing again the ypp_ph step).

Alejandro.

[amolina]

Dear Alejandro,

When i use the secant method i end up with a segmentation error while running G0W0 calculation.
I obtain no error from other solvers. However, when i use the newton solver, it only performs electron-phonon self energy calculation and NO G0W0 calculation
(for electron electron part) as in the case of secant method using the same input file. Is this normal ?

Dear Martin,
indeed it seems a bug. I will check it and I will write you when is solved. In the meanwhile you can use the newton solver.

In the QP file you see that LDA and HF are simply zero, why ?

I am not sure, but I guess they are not calculated when you calculate the QP correction due to the electron-phonon interaction.

From time to time i see unphysical Z factor (larger than 1), why ?

Well, it can happen that the QP approximation is not longer valid for that specific point. Remember that the tutorial uses non-converged parameters.

[martinspenke]

Dear Alejandro,

many thanks for your replies.
Since for now due to technical problems i can not run electron-phonon calculations on my desired systems, i like to know from your experiences that
whether inclusion of dynamical effects increases or decreases the electronic band gap ?

Bests
Martin

[fabri]

Dear all,
i would like to evaluate the lifetime of an exciton state due to electron-phonon interactions in a few simple small oligothiophene molecules, following the steps highlighted in the electron-phonon tutorial on the yambo website.
My question is related on how i have to treat the Gamma divergence of the electron-phonon matrix g since, having an isolated molecule, my calculations would be carried on only at Gamma point for k (electrons) and q (phonons) grids, and the spherical RIM method suggested in the tutorial would give a null result when dealing with a single q=(0,0,0).
In your opinion, is there any other way to treat such divergence?
Best regards

Fabrizio Gala
University of Rome, “La Sapienza”, Italy.

[haseebphysics1]

Dear Yambo developers,

I have generated the ndb.elph_gkkp_fragment_** database files in the SAVE folder! But somehow not able to use them in further calculations!

I want to compute GW and also BSE with electron-phonon interaction but don't know the run-level for the yambo_ph to activate the electron-phonon flags in the input file! In my input, there is no variable appearing for the el-ph in the bse and GW input file!
I tried to manually put the

Code: Select all

el_ph_corr 		       # [R] Electron-Phonon Correlation 

in the BSE input file, but it does not work!

Similarly, there seems to be other phonon variables too as mentioned in this thread like:

Code: Select all

GphBRnge=  50                # [ELPH] G[W] bands range
FANdEtresh=0.1000E-5   eV    # [ELPH] Energy treshold for Fan denominator
DWdEtresh=0.1000E-5    eV    # [ELPH] Energy treshold for DW denominator

I am using Yambo 4.4! while this thread and the variables mentioned above seem to be from a pretty old Yambo version!
However, there must be some el-ph variables in the newer versions too!

After doing QE phonon database and ndb.elph_gkkp_fragment. I tried to do yambo_ph (xyz)
where xyz = -b -o b -k sex -y h -V all -F bse.in (For BSE with el-ph), same run-level we use for the BSE with Yambo!
and xyz = -F yambo.in -g n -p p -V all (For GW + elph), as we do normally.

Input files were generated and I was able to run them with yambo_ph, but there was no phonon variable! and also no indication in the report and log that yambo_ph is reading the saved phonon database in SAVE!
Q2: And can one use Bosonic temp variables in Yambo to calculate BSE@ finite temperatures?

Any help will be highly appreciated!

my bse input file!

Code: Select all

#                                                           
#  __  __   ________   ___ __ __    _______   ______        
# /_/\/_/\ /_______/\ /__//_//_/\ /_______/\ /_____/\       
# \ \ \ \ \\::: _  \ \\::\| \| \ \\::: _  \ \\:::_ \ \      
#  \:\_\ \ \\::(_)  \ \\:.      \ \\::(_)  \/_\:\ \ \ \     
#   \::::_\/ \:: __  \ \\:.\-/\  \ \\::  _  \ \\:\ \ \ \    
#     \::\ \  \:.\ \  \ \\. \  \  \ \\::(_)  \ \\:\_\ \ \   
#      \__\/   \__\/\__\/ \__\/ \__\/ \_______\/ \_____\/   
#                                                           
#                                                           
# GPL Version 4.3.3 Revision 139. (Based on r.16814 h.4b029d
#                        MPI Build                          
#                http://www.yambo-code.org                  
#
em1s                           # [R Xs] Static Inverse Dielectric Matrix
optics                         # [R OPT] Optics
bss                            # [R BSS] Bethe Salpeter Equation solver
bse                            # [R BSE] Bethe Salpeter Equation.
bsk                            # [R BSK] Bethe Salpeter Equation kernel
el_ph_corr 		       # [R] Electron-Phonon Correlation
ElecTemp=  0.02585     eV      # Electronic Temperature
FFTGvecs=  4111        RL      # [FFT] Plane-waves
Chimod= "hartree"              # [X] IP/Hartree/ALDA/LRC/PF/BSfxc
BSEmod= "retarded"             # [BSE] resonant/retarded/coupling
BSKmod= "SEX"                  # [BSE] IP/Hartree/HF/ALDA/SEX
BSSmod= "h"                    # [BSS] (h)aydock/(d)iagonalization/(i)nversion/(t)ddft`
BSENGexx= 26229        RL      # [BSK] Exchange components
BSENGBlk=  5           Ry      # [BSK] Screened interaction block size
#WehCpl                        # [BSK] eh interaction included also in coupling
% KfnQP_E
 0.420000 | 1.000000 | 1.000000 |        # [EXTQP BSK BSS] E parameters  (c/v) eV|adim|adim
%
% BEnRange
  0.00000 | 6.00000 | eV      # [BSS] Energy range
%
% BDmRange
  0.10000 |  0.10000 | eV      # [BSS] Damping range
%
BEnSteps=200                     # [BSS] Energy steps
% BLongDir
 1.000000 | 1.000000 | 1.000000 |        # [BSS] [cc] Electric Field
%
% BSEBands
  2 | 10 |                     # [BSK] Bands range
%
BSHayTrs= -0.02000             # [BSS] Relative [o/o] Haydock treshold. Strict(>0)/Average(<0)
% BndsRnXs
   1 |  40 |                   # [Xs] Polarization function bands
%
NGsBlkXs= 5            Ry      # [Xs] Response block size
% DmRngeXs
  0.10000 |  0.10000 | eV      # [Xs] Damping range
%
% LongDrXs
 1.000000 | 1.000000 | 1.000000 |        # [Xs] [cc] Electric Field
%

Thanks,