about QpntsRXs

Concerns issues with computing quasiparticle corrections to the DFT eigenvalues - i.e., the self-energy within the GW approximation (-g n), or considering the Hartree-Fock exchange only (-x)

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zsjan
Posts: 26
Joined: Wed Aug 27, 2014 8:09 am

about QpntsRXs

Post by zsjan » Fri Sep 05, 2014 9:19 am

Dear all:
In GW calculations, I know the following five parameters should be tested to be converged:
EXXRLvcs, QpntsRXp, NGsBlkXp, BndsRnXp and GbndRnge

However, when I following the tutorial to issue the command
yambo -b -k hartree -g n -p c
the generated input file has no parameter of QpntsRXp like this:
#
# GPL Version 3.4.1 Revision 3187
# http://www.yambo-code.org
#
em1s # [R Xs] Static Inverse Dielectric Matrix
gw0 # [R GW] GoWo Quasiparticle energy levels
cohsex # [R Xp] COlumb Hole Screened EXchange
HF_and_locXC # [R XX] Hartree-Fock Self-energy and Vxc
EXXRLvcs= 2085 RL # [XX] Exchange RL components
Chimod= "Hartree" # [X] IP/Hartree/ALDA/LRC/BSfxc
% BndsRnXs
1 | 50 | # [Xs] Polarization function bands
%
NGsBlkXs= 1 RL # [Xs] Response block size
% LongDrXs
1.000000 | 0.000000 | 0.000000 | # [Xs] [cc] Electric Field
%
% GbndRnge
1 | 50 | # [GW] G[W] bands range
%
%QPkrange # [GW] QP generalized Kpoint/Band indices
1| 8| 1| 50|
%
%QPerange # [GW] QP generalized Kpoint/Energy indices
1| 8| 0.0|-1.0|
%
Is it reasonable or it should be added manually?
By the way, I get NaN in E-E0 column. What is the possible reason for this fact?


Shijun Zhao
Peking University
Shijun Zhao
College of Engineering
Peking University

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Daniele Varsano
Posts: 4198
Joined: Tue Mar 17, 2009 2:23 pm
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Re: about QpntsRXs

Post by Daniele Varsano » Fri Sep 05, 2014 10:33 pm

Dear Shijun,
in GW you need to use all the Q points in order to integrate in the whole Brilluoin zone, so it is not needed in input.
In order to converge with respect the Qpoints, you need to increase the k points in the ground state calculations.
About the NaN, first note that your input file it is not a GW calculation but a COHSEX run. It is impossible to understand what is going on with the information you provided, beside the input, please post also the report file.
Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/

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