output file of BSE
Moderators: Davide Sangalli, Daniele Varsano, andrea.ferretti, andrea marini, Conor Hogan, myrta gruning

 Posts: 224
 Joined: Fri Apr 09, 2010 12:30 pm
output file of BSE
Dear all"
I have calculate my 2D rectangle unitcell including 4C atoms and 2O atoms with pwscf v4.1.2, then I do a BSE calculation.I type >yambo o b b y h,and edit input file as:
optics # [R OPT] Optics
bse # [R BSK] Bethe Salpeter Equation.
em1s # [R Xs] Static Inverse Dielectric Matrix
bss # [R BSS] Bethe Salpeter Equation solver
BSresKmod= "xc" # [BSK] Resonant Kernel mode. (`x`;`c`;`d`)
% BSEBands
1  18  # [BSK] Bands range
%
BSENGBlk= 1 RL # [BSK] Screened interaction block size
BSENGexx= 2027 RL # [BSK] Exchange components
% QpntsRXs
1  14  # [Xs] Transferred momenta
%
% BndsRnXs
1  18  # [Xs] Polarization function bands
%
NGsBlkXs= 1 RL # [Xs] Response block size
% LongDrXs
1.000000  0.000000  0.000000  # [Xs] [cc] Electric Field
%
BSSmod= "h" # [BSS] Solvers `h/d/i/t`
% BEnRange
0.00000  10.00000  eV # [BSS] Energy range
%
% BDmRange
0.10000  0.10000  eV # [BSS] Damping range
%
BEnSteps= 100 # [BSS] Energy steps
% BLongDir
1.000000  0.000000  0.000000  # [BSS] [cc] Electric Field
%
Then type >yambo N, it seems to go well .and I got the optical spectrum of it, but this result is the same like the RPA one.The two OAS agree very well. Is the result believable?
The RPA input file is:
optics # [R OPT] Optics
chi # [R CHI] Dyson equation for Chi.
% QpntsRXd
1  14  # [Xd] Transferred momenta
%
% BndsRnXd
1  18  # [Xd] Polarization function bands
%
NGsBlkXd= 1 RL # [Xd] Response block size
% EnRngeXd
0.00000  10.00000  eV # [Xd] Energy range
%
% DmRngeXd
0.10000  0.10000  eV # [Xd] Damping range
%
ETStpsXd= 100 # [Xd] Total Energy steps
% LongDrXd
1.000000  0.000000  0.000000  # [Xd] [cc] Electric Field
%
What is the problem??
When I calculate bulk Si, the speed is slow.But my unitcell including 6 atoms is very quick as RPA procedure. I do not know why??
Thanks in advance !!
SDWang
I have calculate my 2D rectangle unitcell including 4C atoms and 2O atoms with pwscf v4.1.2, then I do a BSE calculation.I type >yambo o b b y h,and edit input file as:
optics # [R OPT] Optics
bse # [R BSK] Bethe Salpeter Equation.
em1s # [R Xs] Static Inverse Dielectric Matrix
bss # [R BSS] Bethe Salpeter Equation solver
BSresKmod= "xc" # [BSK] Resonant Kernel mode. (`x`;`c`;`d`)
% BSEBands
1  18  # [BSK] Bands range
%
BSENGBlk= 1 RL # [BSK] Screened interaction block size
BSENGexx= 2027 RL # [BSK] Exchange components
% QpntsRXs
1  14  # [Xs] Transferred momenta
%
% BndsRnXs
1  18  # [Xs] Polarization function bands
%
NGsBlkXs= 1 RL # [Xs] Response block size
% LongDrXs
1.000000  0.000000  0.000000  # [Xs] [cc] Electric Field
%
BSSmod= "h" # [BSS] Solvers `h/d/i/t`
% BEnRange
0.00000  10.00000  eV # [BSS] Energy range
%
% BDmRange
0.10000  0.10000  eV # [BSS] Damping range
%
BEnSteps= 100 # [BSS] Energy steps
% BLongDir
1.000000  0.000000  0.000000  # [BSS] [cc] Electric Field
%
Then type >yambo N, it seems to go well .and I got the optical spectrum of it, but this result is the same like the RPA one.The two OAS agree very well. Is the result believable?
The RPA input file is:
optics # [R OPT] Optics
chi # [R CHI] Dyson equation for Chi.
% QpntsRXd
1  14  # [Xd] Transferred momenta
%
% BndsRnXd
1  18  # [Xd] Polarization function bands
%
NGsBlkXd= 1 RL # [Xd] Response block size
% EnRngeXd
0.00000  10.00000  eV # [Xd] Energy range
%
% DmRngeXd
0.10000  0.10000  eV # [Xd] Damping range
%
ETStpsXd= 100 # [Xd] Total Energy steps
% LongDrXd
1.000000  0.000000  0.000000  # [Xd] [cc] Electric Field
%
What is the problem??
When I calculate bulk Si, the speed is slow.But my unitcell including 6 atoms is very quick as RPA procedure. I do not know why??
Thanks in advance !!
SDWang
 Daniele Varsano
 Posts: 2655
 Joined: Tue Mar 17, 2009 2:23 pm
 Contact:
Re: output file of BSE
Dear Shudong,
I don't know what are you calculating, but note that:
In BSE you are considering just one block in the screening interaction.
when a BSE calculation is performed, you should consider quasiparticle
energies, so in practice you have to correct your eigenvalues by a previous
GW calculation or some empirical corrections.
I suggest you to take a look to the documentation.
Best,
Daniele
I don't know what are you calculating, but note that:
In BSE you are considering just one block in the screening interaction.
In the RPA you are not including local fields:BSENGBlk= 1 RL # [BSK] Screened interaction block size
moreover:NGsBlkXd= 1 RL # [Xd] Response block size
when a BSE calculation is performed, you should consider quasiparticle
energies, so in practice you have to correct your eigenvalues by a previous
GW calculation or some empirical corrections.
I suggest you to take a look to the documentation.
Best,
Daniele
Dr. Daniele Varsano
S3CNR Institute of Nanoscience and MaX Center, Italy
MaX  Materials design at the Exascale
http://www.nano.cnr.it
http://www.maxcentre.eu/
S3CNR Institute of Nanoscience and MaX Center, Italy
MaX  Materials design at the Exascale
http://www.nano.cnr.it
http://www.maxcentre.eu/
 andrea marini
 Posts: 450
 Joined: Mon Mar 16, 2009 4:27 pm
 Contact:
Re: output file of BSE
... and I strongly invite you to run and study (critically) ALL the tutorials before running any production run.Daniele Varsano wrote: I suggest you to take a look to the documentation.
Andrea MARINI
Istituto di Struttura della Materia, CNR, (Italy)
Istituto di Struttura della Materia, CNR, (Italy)

 Posts: 224
 Joined: Fri Apr 09, 2010 12:30 pm
Re: output file of BSE
Thank you for your reply.

 Posts: 224
 Joined: Fri Apr 09, 2010 12:30 pm
Re: output file of BSE
Dear developers:
After complishing my BSE calculation, I got some data as following :
E/ev e/Im e/Re eo/Im eo/Re e`/Im e`/Re
I wanna know the difference among e/Im,eo/Im and e`/Im, Which is the last data I used to plot absorption spectrum?
Thanks!
SDWang
After complishing my BSE calculation, I got some data as following :
E/ev e/Im e/Re eo/Im eo/Re e`/Im e`/Re
I wanna know the difference among e/Im,eo/Im and e`/Im, Which is the last data I used to plot absorption spectrum?
Thanks!
SDWang
 myrta gruning
 Posts: 309
 Joined: Tue Mar 17, 2009 11:38 am
 Contact:
Re: output file of BSE
Hallo Shudong Wang,
e/Im gives you the absorption spectrum within the BSE level of theory.
eo/Im is the absorption spectrum from the independent particle approximation
The comparison of these two curves gives the measure in which manybody effects are important.
e`/Im appears when you are solving the BSE Hamiltonian with Haydock (sec 3.2 of the yambo paper).
This is an iterative algorithm. At each iteration the algorithm produces a better approximation for the spectrum. The algorithm stops when the diff between the spectrum at two successive iteration is lower than a threshold.
So e/Im is the spectrum for the last iteration, and e`/Im the one for the secondlast iteration. In principle they should be (almost) indistinguishable, if the algorithm is well converged.
Regards,
m
e/Im gives you the absorption spectrum within the BSE level of theory.
eo/Im is the absorption spectrum from the independent particle approximation
The comparison of these two curves gives the measure in which manybody effects are important.
e`/Im appears when you are solving the BSE Hamiltonian with Haydock (sec 3.2 of the yambo paper).
This is an iterative algorithm. At each iteration the algorithm produces a better approximation for the spectrum. The algorithm stops when the diff between the spectrum at two successive iteration is lower than a threshold.
So e/Im is the spectrum for the last iteration, and e`/Im the one for the secondlast iteration. In principle they should be (almost) indistinguishable, if the algorithm is well converged.
Regards,
m
Dr Myrta Grüning
Atomistic Simulation Centre
Queen's University Belfast  Northern Ireland
http://www.researcherid.com/rid/B15152009
Atomistic Simulation Centre
Queen's University Belfast  Northern Ireland
http://www.researcherid.com/rid/B15152009

 Posts: 224
 Joined: Fri Apr 09, 2010 12:30 pm
Re: output file of BSE
Thank you!Daniele Varsano wrote:Dear Shudong,
I don't know what are you calculating, but note that:
In BSE you are considering just one block in the screening interaction.In the RPA you are not including local fields:BSENGBlk= 1 RL # [BSK] Screened interaction block sizemoreover:NGsBlkXd= 1 RL # [Xd] Response block size
when a BSE calculation is performed, you should consider quasiparticle
energies, so in practice you have to correct your eigenvalues by a previous
GW calculation or some empirical corrections.
I suggest you to take a look to the documentation.
Best,
Daniele
I have another quetion about scissor in GW calculation.
According to your opinions, before I have a BSE calculation,I have to firstly perform a GW process(Is it right?), and I would get the quasiparticle
energies. Is the "scissor" in BSE=E_QPE_LDA???? But in GW calculation, it also have the option "scissor", how can I determine this when I perform GW calculation??
Thanks!
 Daniele Varsano
 Posts: 2655
 Joined: Tue Mar 17, 2009 2:23 pm
 Contact:
Re: output file of BSE
Right, this is the definition of the scissor. About your second question, just ignore it, the default value isIs the "scissor" in BSE=E_QPE_LDA???? But in GW calculation, it also have the option "scissor", how can I determine this when I perform GW calculation??
0 1 1
which means, no scissor.
Best,
Daniele
Dr. Daniele Varsano
S3CNR Institute of Nanoscience and MaX Center, Italy
MaX  Materials design at the Exascale
http://www.nano.cnr.it
http://www.maxcentre.eu/
S3CNR Institute of Nanoscience and MaX Center, Italy
MaX  Materials design at the Exascale
http://www.nano.cnr.it
http://www.maxcentre.eu/

 Posts: 224
 Joined: Fri Apr 09, 2010 12:30 pm

 Posts: 148
 Joined: Sat Aug 17, 2019 2:48 pm
Re: output file of BSE
Hi, dear Yambo team,
I'm new in using Yambo code. My first objective currently is to find optical properties of bulk semiconductors solving BSE. I'm having a hard time locating the output file of the calculation of BSE! I followed the Yambo research paper (Yambo: An ab initio tool for excited state calculations) for commandline options. Moreover, I am also attaching the input and output files (I found relevant). The name of the output file which is mentioned in the paper "o.eps_q001bh" can not be found in the working directory or any other file containing the data to plot, hence I'm uncertain from where to get data to plot the absorption curve! Maybe it can be due to the reason I am not passing the input commands for parallel calculation correctly? Anticipating your kind response,
Regards,
Haseeb Ahmad,
LUMS, Pakistan.
I'm new in using Yambo code. My first objective currently is to find optical properties of bulk semiconductors solving BSE. I'm having a hard time locating the output file of the calculation of BSE! I followed the Yambo research paper (Yambo: An ab initio tool for excited state calculations) for commandline options. Moreover, I am also attaching the input and output files (I found relevant). The name of the output file which is mentioned in the paper "o.eps_q001bh" can not be found in the working directory or any other file containing the data to plot, hence I'm uncertain from where to get data to plot the absorption curve! Maybe it can be due to the reason I am not passing the input commands for parallel calculation correctly? Anticipating your kind response,
Regards,
Haseeb Ahmad,
LUMS, Pakistan.
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Haseeb Ahmad
MS  Physics,
LUMS  Pakistan
MS  Physics,
LUMS  Pakistan