Bethe-Salpeter calculation without absorption spectrum

[ljzhou86]

I do a Bethe-Salpeter calculation to obtain the absorption for silicene system.
In the last step (yambo -o b -y d), some warnings come out, how to resorle it?
<---> [WARNING] The system is a metal but Drude term not included.
<---> [WARNING] Missing non-local pseudopotential contribution

In addition, when I set BSKmod= "SEX", I cannot obtain the spectrum, namely, o.eps_q1_sex, o.eel_q1_sex; while for BSKmod="IP", such output file can obtain. what's the reason?

the yambo.in is as followed:
optics # [R OPT] Optics
bse # [R BSE] Bethe Salpeter Equation.
BSEmod= "coupling" # [BSE] resonant/causal/coupling
BSKmod= "SEX" # [BSE] IP/Hartree/HF/ALDA/SEX
% BEnRange
0.00000 | 10.00000 | eV # [BSS] Energy range
%
% BDmRange
0.10000 | 0.10000 | eV # [BSS] Damping range
%
BSSmod= "d"
BEnSteps= 100 # [BSS] Energy steps
% BLongDir
1.000000 | 0.000000 | 0.000000 | # [BSS] [cc] Electric Field
%
% BSEBands
2 | 8 | # [BSK] Bands range
%

Another question, in the calculation of the screening, how to set the value of the parameter NGsBlkXs generality? NGsBlkXp~=1/10*EXXRLvcs??

[Daniele Varsano]

Dear Dr. Zhou Liu-Jiang,
can you post the report file of your BSE calculation?
About the warning, they should be self-explaining. You can include a Drude term accounting for the interband transitions.
The non local part coming from the pseudos in the oscillators is missing in your calculations, I presume you are calculating the ground state with Quantum Espresso. In the development version of the code this term has been added.
Best
Daniele

[ljzhou86]

Yes, I do hte ground state with QE. How to include a Drude term accounting for the interband transitions? Just add parameter DrudeW in the yambo.in?
can you post the report file of your BSE calculation?

the report file of my bse calculation is as followed:

::: ::: ::: :::: :::: ::::::::: ::::::::
:+: :+: :+: :+: +:+:+: :+:+:+ :+: :+: :+: :+:
+:+ +:+ +:+ +:+ +:+ +:+:+ +:+ +:+ +:+ +:+ +:+
+#++: +#++:++#++: +#+ +:+ +#+ +#++:++#+ +#+ +:+
+#+ +#+ +#+ +#+ +#+ +#+ +#+ +#+ +#+
#+# #+# #+# #+# #+# #+# #+# #+# #+#
### ### ### ### ### ######### ########

GPL Version 3.4.0 Revision 2132
http://www.yambo-code.org

YAMBO@AI2.single x 016 CPUs * 05/21/2013 17:33

[01] Files & I/O Directories
============================

CORE databases in .
Additional I/O in .
Communications in .
Input file is yambo.in
Report file is ./r_optics_bse_02
Log file is ./l_optics_bse_02

[RD./SAVE//ns.db1]------------------------------------------
Bands : 20
K-points : 21
G-vectors [RL space]: 30249
Components [wavefunctions]: 3795
Symmetries [spatial]: 4
Spinor components : 1
Spin polarizations : 1
Temperature [ev]: 0.136057
Electrons : 8.000000
WF G-vectors : 4795
Max atoms/species : 2
No. of atom species : 1
Magnetic symmetries : no
- S/N 003953 --------------------------- v.03.04.00 r.2132 -

[02] CORE Variables Setup
=========================


[02.01] Unit cells
==================

Unit cell is Unknown

... containing 2Si atoms

... with scaling factors [a.u.]: 6.28452 7.25674 29.82726

Direct Lattice(DL) unit cell [iru]
A1 = 1.000000 -0.500000 0.000000
A2 = 0.000000 1.000000 0.000000
A3 = 0.000000 0.000000 1.000000

DL volume [au]: 1360.

Reciprocal Lattice(RL) unit cell [iku]
B1 = 1.000000 0.000000 0.000000
B2 = 0.500000 1.000000 0.000000
B3 = 0.000000 0.000000 1.000000


[02.02] Symmetries
==================

DL (S)ymmetries [cc]
[S1] 1.000000 0.000000 0.000000 0.000000 1.000000 0.000000 0.000000 0.000000 1.000000
[S2]-1.000000 0.000000 0.000000 0.000000 1.000000 0.000000 0.000000 0.000000 -1.000000
[S3]-1.000000 0.000000 0.000000 0.000000 -1.000000 0.000000 0.000000 0.000000 -1.000000
[S4] 1.000000 0.000000 0.000000 0.000000 -1.000000 0.000000 0.000000 0.000000 1.000000

[SYMs] K-space Time-reversal not included
[SYMs] Spatial inversion 3 is a symmetry
[SYMs] Group table built correctly

[02.03] RL shells
=================

Shells, format: [S#] G_RL(mHa)

[S612]:10243(0.2918E+5) [S611]:10219(0.2918E+5) [S610]:10207(0.2915E+5) [S609]:10183(0.2915E+5)
[S608]:10159(0.2904E+5) [S607]:10135(0.2899E+5) [S606]:10111(0.2898E+5) [S605]:10099(0.2884E+5)
[S604]:10075(0.2884E+5) [S603]:10039(0.2875E+5) [S602]:10037(0.2873E+5) [S601]:10025(0.2872E+5)
[S600]:10013(0.2869E+5) [S599]:9989(0.2868E+5) [S598]:9965(0.2868E+5) [S597]:9953(0.2867E+5)
[S596]:9929(0.2867E+5) [S595]:9917(0.2866E+5) [S594]:9905(0.2858E+5) [S593]:9881(0.2851E+5)
[S592]:9857(0.2849E+5) [S591]:9845(0.2849E+5) [S590]:9833(0.2837E+5) [S589]:9809(0.2834E+5)
[S588]:9797(0.2828E+5) [S587]:9773(0.2827E+5) [S586]:9749(0.2824E+5) [S585]:9713(0.2821E+5)
...
[S12]:67( 854.7830) [S11]:55( 798.7401) [S10]:53( 699.4723) [S9]:41( 588.5362)
[S8]:29( 554.6807) [S7]:27( 521.9745) [S6]:15( 499.7874) [S5]:9( 354.9956)
[S4]:7( 199.6850) [S3]:5( 88.74890) [S2]:3( 22.18723) [S1]:1( 0.000000)

[02.04] K-grid lattice
======================

Compatible Grid is 2D
B1 [rlu]=-0.125000 0.000000 0.000000
B2 = 0.125000 -0.125000 0.000000
Grid dimensions : 8 8
K lattice UC volume [au]: 0.0028

[02.05] Energies [ev] & Occupations
===================================

Fermi Level [ev]:-2.448283
Electronic Temp. [ev K]: 0.1361 1579.
Bosonic Temp. [ev K]: 0.1361 1579.
El. density [cm-3]: 0.397E+23
States summary : Full Metallic Empty
0001-0002 0003-0006 0007-0020

[WARNING]Metallic system
N of el / N of met el: 8.000000 4.000597
Average metallic occ.: 1.000149
X BZ K-points : 64

Energy unit is electronVolt [eV]

*X* K [1] : 0.000000 0.000000 0.000000 (iku) * Comp.s 3773 * weight 0.01562
E -11.04385 -3.18487 -1.14546 -1.14545 2.17189 2.54266 3.10559 3.10560
E 4.503660 4.733095 6.179698 6.935169 8.050261 8.837836 8.854569 8.854573
E 10.67334 11.10378 11.92345 11.92345

*X* K [2] : 0.06250 0.125000 0.000000 (iku) * Comp.s 3795 * weight 0.06250
E -10.85944 -3.08163 -2.26603 -1.45008 2.46211 2.66468 3.68852 3.76073
E 4.708958 4.861833 5.806867 7.127545 7.402853 8.410245 9.277146 9.910911
E 10.77600 11.25720 11.80974 12.63702

*X* K [3] : 0.125000 0.250000 0.000000 (iku) * Comp.s 3771 * weight 0.06250
E -10.31568 -4.36286 -2.39553 -1.99927 1.81944 2.66331 4.44361 5.30885
E 5.32440 5.73846 5.89969 7.51864 7.77975 7.80533 8.96652 10.87081
E 11.17539 11.60831 12.08856 12.30538

*X* K [4] : 0.187500 0.375000 0.000000 (iku) * Comp.s 3781 * weight 0.06250
E -9.467709 -6.118266 -2.412468 -1.617748 1.231375 1.693405 4.819109 6.307610
E 6.617088 6.709292 7.327913 7.926909 8.176348 8.825269 9.104580 9.373176
E 9.97432 10.43016 12.16580 12.20637

*X* K [5] :-0.250000 -0.500000 0.000000 (iku) * Comp.s 3776 * weight 0.03125
E -8.774879 -7.127979 -2.559708 -1.000898 0.655069 1.250331 5.583820 6.496341
E 6.67719 7.45278 7.78927 8.16538 8.25985 8.66336 10.04894 10.06973
E 10.22291 10.35300 10.61537 10.70038

*X* K [6] : 0.125000 0.000000 0.000000 (iku) * Comp.s 3795 * weight 0.03125
E -10.85944 -3.08163 -2.26602 -1.45009 2.46211 2.66468 3.68852 3.76073
E 4.708958 4.861833 5.806868 7.127545 7.402853 8.410242 9.277146 9.910909
E 10.77600 11.25720 11.80974 12.63702

*X* K [7] : 0.187500 0.125000 0.000000 (iku) * Comp.s 3783 * weight 0.06250
E -10.49465 -3.77089 -2.52884 -2.12387 2.67688 3.17338 3.27140 4.70450
E 5.10347 5.62550 5.79779 7.23036 7.57781 7.69639 10.04578 10.79873
E 11.34715 11.47514 11.76590 12.43635

*X* K [8] : 0.250000 0.250000 0.000000 (iku) * Comp.s 3780 * weight 0.06250
E -9.788876 -5.365951 -2.871093 -1.895718 2.007553 2.737252 4.617747 5.039539
E 5.72758 6.26104 6.38337 8.03033 8.34912 8.43473 9.76182 10.41216
E 11.08488 11.17386 11.60591 12.02273

*X* K [9] : 0.312500 0.375000 0.000000 (iku) * Comp.s 3769 * weight 0.06250
E -8.875697 -6.819421 -3.257742 -1.046250 0.896866 2.383827 5.120522 5.774484
E 6.944343 7.249425 7.548685 7.882385 8.843994 9.173725 9.459765 9.601648
E 9.98882 10.43489 11.19029 11.40662

*X* K [10] :-0.125000 -0.500000 0.000000 (iku) * Comp.s 3769 * weight 0.06250
E -8.875696 -6.819422 -3.257741 -1.046250 0.896865 2.383827 5.120523 5.774484
E 6.944344 7.249424 7.548686 7.882386 8.843994 9.173725 9.459765 9.601647
E 9.98882 10.43489 11.19029 11.40662

*X* K [11] : -0.06250 -0.375000 0.000000 (iku) * Comp.s 3780 * weight 0.06250
E -9.788875 -5.365953 -2.871090 -1.895718 2.007553 2.737251 4.617747 5.039542
E 5.72758 6.26104 6.38337 8.03032 8.34911 8.43473 9.76182 10.41216
E 11.08488 11.17386 11.60591 12.02273

*X* K [12] : 0.000000 -0.250000 0.000000 (iku) * Comp.s 3783 * weight 0.03125
E -10.49465 -3.77090 -2.52884 -2.12386 2.67688 3.17338 3.27141 4.70450
E 5.10347 5.62550 5.79778 7.23036 7.57781 7.69639 10.04578 10.79873
E 11.34715 11.47514 11.76590 12.43636

*X* K [13] : 0.250000 0.000000 0.000000 (iku) * Comp.s 3771 * weight 0.03125
E -10.31568 -4.36286 -2.39553 -1.99927 1.81944 2.66331 4.44362 5.30885
E 5.32440 5.73846 5.89969 7.51864 7.77974 7.80533 8.96652 10.87081
E 11.17539 11.60830 12.08856 12.30538

*X* K [14] : 0.312500 0.125000 0.000000 (iku) * Comp.s 3780 * weight 0.06250
E -9.788876 -5.365949 -2.871094 -1.895718 2.007554 2.737249 4.617747 5.039542
E 5.72758 6.26104 6.38337 8.03032 8.34912 8.43473 9.76182 10.41216
E 11.08488 11.17386 11.60591 12.02273

*X* K [15] : 0.375000 0.250000 0.000000 (iku) * Comp.s 3756 * weight 0.06250
E -8.958785 -6.462696 -3.881148 -1.108610 1.171064 4.491455 4.559889 5.009202
E 5.46312 7.08110 7.36872 8.24844 9.00137 9.46182 9.52727 10.19189
E 10.39583 10.48785 10.65628 10.95673

*X* K [16] : 0.437500 0.375000 0.000000 (iku) * Comp.s 3746 * weight 0.06250
E -8.189316 -7.334817 -4.246624 -0.394107 0.410009 4.229656 4.528518 6.396451
E 6.585554 7.622855 7.649361 8.414522 8.615709 8.622479 8.830469 9.200205
E 10.19239 10.51426 10.56768 10.84871

*X* K [17] : 0.000000 -0.500000 0.000000 (iku) * Comp.s 3756 * weight 0.03125
E -8.958783 -6.462701 -3.881145 -1.108610 1.171063 4.491456 4.559890 5.009204
E 5.46312 7.08110 7.36872 8.24844 9.00137 9.46182 9.52727 10.19188
E 10.39583 10.48785 10.65628 10.95673

*X* K [18] : 0.375000 0.000000 0.000000 (iku) * Comp.s 3781 * weight 0.03125
E -9.467710 -6.118261 -2.412472 -1.617749 1.231374 1.693405 4.819109 6.307610
E 6.617087 6.709292 7.327914 7.926909 8.176349 8.825270 9.104580 9.373176
E 9.97432 10.43016 12.16580 12.20637

*X* K [19] : 0.437500 0.125000 0.000000 (iku) * Comp.s 3769 * weight 0.06250
E -8.875700 -6.819416 -3.257745 -1.046251 0.896868 2.383824 5.120521 5.774484
E 6.944345 7.249425 7.548686 7.882386 8.843994 9.173725 9.459765 9.601649
E 9.98882 10.43489 11.19029 11.40662

*X* K [20] : 0.500000 0.250000 0.000000 (iku) * Comp.s 3746 * weight 0.03125
E -8.189321 -7.334811 -4.246626 -0.394109 0.410011 4.229655 4.528515 6.396451
E 6.585556 7.622856 7.649361 8.414523 8.615710 8.622478 8.830469 9.200205
E 10.19239 10.51426 10.56768 10.84871

*X* K [21] :-0.500000 0.000000 0.000000 (iku) * Comp.s 3776 * weight 0.01563
E -8.774884 -7.127971 -2.559711 -1.000900 0.655073 1.250327 5.583819 6.496341
E 6.67719 7.45278 7.78927 8.16538 8.25985 8.66336 10.04894 10.06973
E 10.22291 10.35300 10.61537 10.70038

[03] Transferred momenta grid
=============================

[RD./SAVE//ndb.kindx]---------------------------------------
Polarization last K : 21
QP states : 1 21
X grid is uniform :yes
BS scattering :yes
- S/N 003953 --------------------------- v.03.04.00 r.2132 -

IBZ Q-points : 21
BZ Q-points : 64

Q [00001] : 0.00 0.00 0.00 (iku) * weight 0.01562
Q [00002] : 0.06250 0.12500 0.00000 (iku) * weight 0.06250
Q [00003] : 0.125000 0.250000 0.000000 (iku) * weight 0.06250
Q [00004] : 0.187500 0.375000 0.000000 (iku) * weight 0.06250
Q [00005] :-0.250000 -0.500000 0.000000 (iku) * weight 0.03125
Q [00006] : 0.125000 0.000000 0.000000 (iku) * weight 0.03125
Q [00007] : 0.187500 0.125000 0.000000 (iku) * weight 0.06250
Q [00008] : 0.250000 0.250000 0.000000 (iku) * weight 0.06250
Q [00009] : 0.312500 0.375000 0.000000 (iku) * weight 0.06250
Q [00010] :-0.125000 -0.500000 0.000000 (iku) * weight 0.06250
Q [00011] : -0.06250 -0.37500 0.00000 (iku) * weight 0.06250
Q [00012] : 0.000000 -0.250000 0.000000 (iku) * weight 0.03125
Q [00013] : 0.250000 0.000000 0.000000 (iku) * weight 0.03125
Q [00014] : 0.312500 0.125000 0.000000 (iku) * weight 0.06250
Q [00015] : 0.375000 0.250000 0.000000 (iku) * weight 0.06250
Q [00016] : 0.437500 0.375000 0.000000 (iku) * weight 0.06250
Q [00017] : 0.000000 -0.500000 0.000000 (iku) * weight 0.03125
Q [00018] : 0.375000 0.000000 0.000000 (iku) * weight 0.03125
Q [00019] : 0.437500 0.125000 0.000000 (iku) * weight 0.06250
Q [00020] : 0.500000 0.250000 0.000000 (iku) * weight 0.03125
Q [00021] :-0.500000 0.000000 0.000000 (iku) * weight 0.01563

[03.01] Main loop
=================


[WARNING] The system is a metal but Drude term not included.
[RD./SAVE//ndb.dipoles]-------------------------------------
Brillouin Zone Q/K grids (IBZ/BZ): 21 64 21 64
RL vectors (WF): 4809
Electronic Temperature [K]: 1579.
Bosonic Temperature [K]: 1579.
X band range : 1 20
X e/h energy range [ev]:-1.000000 -1.000000
Metallic bands : 6
Filled bands : 2
RL vectors in the sum : 4809
[r,Vnl] included :no
Transitions ordered :yes
Using shifted grids :no
Field momentum norm :0.1000E-4
Wavefunctions :Perdew, Burke & Ernzerhof(X)+Perdew, Burke & Ernzerhof(C)
- S/N 003953 --------------------------- v.03.04.00 r.2132 -

[WARNING] Missing non-local pseudopotential contribution

[04] Bethe-Salpeter Kernel
==========================

[RD./SAVE//ndb.BS_Q1]---------------------------------------
Brillouin Zone Q/K grids (IBZ/BZ): 21 64 21 64
RL vectors (WF): 4809
Coulomb cutoff potential :none
BS kernel wavefunctions :Perdew, Burke & Ernzerhof(X)+Perdew, Burke & Ernzerhof(C)
Static diel. fun. energies :Perdew, Burke & Ernzerhof(X)+Perdew, Burke & Ernzerhof(C)
wavefunctions :Perdew, Burke & Ernzerhof(X)+Perdew, Burke & Ernzerhof(C)
BSK|Identifier : 5421
|Dimension : 1034
|Bands : 2 8
|Exchange [res]:yes
|Correlation [res]:yes
|Kernel`s coupling :yes
|Exchange [cpl]:yes
|W interaction is bare :no
|Correlation [cpl]:no
|ALDA kernel in R-space :no
|RL vectors [exchange]: 15
|RL vectors [correlation]: 1
|E/h energy range [ev]:-1.000000 -1.000000
|Coupling range [o/o]: 100.0000 100.0000
W |Interaction is diagonal :no
|Matrix size : 501
|Bands : 1 20
|e/h energy range [ev]:-1.000000 -1.000000
|Poles [o/o]: 100.0000
|Rl vectors in the sum : 4809
|[r,Vnl] included :no
|Field direction :0.1000E-4 0.000 0.000
|Coulomb Cutoff :none
|xc-Kernel :none
RIM|RL components [col]:0
|Random points [col]:0
- S/N 003953 --------------------------- v.03.04.00 r.2132 -

[05] Game Over & Game summary
=============================

YAMBO@AI2.single x 016 CPUs * 05/21/2013 17:33 [start]
05/21/2013 17:33 [end]
.-ACKNOWLEDGMENT
|
| The users of YAMBO have little formal obligations with respect to
| the YAMBO group (those specified in the GNU General Public
| License, http://www.gnu.org/copyleft/gpl.txt). However, it is
| common practice in the scientific literature, to acknowledge the
| efforts of people that have made the research possible. In this
| spirit, please find below the reference we kindly ask you to use
| in order to acknowledge YAMBO:
|
| Yambo: An ab initio tool for excited state calculations
| A. Marini, C. Hogan, M. Gr"uning, D. Varsano
| Computer Physics Communications 180, 1392 (2009).
|

.-Input file : yambo.in
| optics # [R OPT] Optics
| bse # [R BSE] Bethe Salpeter Equation.
| FFTGvecs= 4809 RL # [FFT] Plane-waves
| BSEmod= "coupling" # [BSE] resonant/causal/coupling
| BSKmod= "SEX" # [BSE] IP/Hartree/HF/ALDA/SEX
| % BEnRange
| 0.00000 | 10.00000 | eV # [BSS] Energy range
| %
| % BDmRange
| 0.10000 | 0.10000 | eV # [BSS] Damping range
| %
| BEnSteps= 100 # [BSS] Energy steps
| % BLongDir
| 0.1000E-4 | 0.000 | 0.000 | # [BSS] [cc] Electric Field
| %
| % BSEBands
| 2 | 8 | # [BSK] Bands range
| %

How about the other two problems? Thank u.

[Daniele Varsano]

Dr. Zhou Liu-Jiang,
the problem you do not have the output is due to the fact that the excitonic matrix has not been diagonalized.
In your post you claim you used the -y d option to generate the input, but for some reason the diagonalization part is missing in the input.
You should have the "bss" runlevel and variable associated see e.g.:
http://www.yambo-code.org/input_file/ya ... -diago.php
Even if you have "BSSmod= "d" the bss keyword is missing at the beginning of the input file.

Try to regenerate the input file (yambo -y d) and look if the needed variable appears. You can also generate with
yambo -o b -y d, and the bse part relative to the building of the excitonic matrix should appear as you calculated as Yambo
look to the existing database when generating input.

Not related to your problem, anyway note:
you are using very few Gvectors in the exchange part |RL vectors [exchange]: 15
you can set this variable using BSENGexx=, or ALLGexx. With the latter option you consider all the Gvec available for the exchange, ususally
this is not an heavy part of the calculation and you can include all of them.

Another question, in the calculation of the screening, how to set the value of the parameter NGsBlkXs generality? NGsBlkXp~=1/10*EXXRLvcs??

Please not that NGsBlkXs and NGsBlkXp are not the same variable, one is the static screening you need for the BSE while NGsBlkXp is the dynamical one you need for the GW part. I do not know where the rule you wrote comes from, in general NGsBlkXs has to be brought to convergence, I do not know any rule.

In order to include the Drude part, the variable should be DrudeWBS.

Best,

Daniele

[ljzhou86]

I can not generate the needed variable (bss) by using "yambo -o b -y d", while " yambo -y d " can achieve.

what's more, the Gvectors in the exchange part is still 15 when I use variable ALLGexx, why?

How to do a efficient convergence for NGsBlkXs? I mean, do convergence by seting NGsBlkXs "20, 50, 80,110,140" or "100, 200, 300, 400", or "200, 400, 600," .... What's the rough rule for such test? Same with the MaxGvecs. Maybe this problem looks a bit naive but frustrated me for a long time. Thank u

[ljzhou86]

how to use the variable ? I just add "DrudeWBS" in yambo.in without seting any value,is it right? Maybe it is wrong. I found such warning still appeared after adding"DrudeWBS" in yambo.in as followed:
<---> [01] Files & I/O Directories
<---> [02] CORE Variables Setup
<---> [02.01] Unit cells
<---> [02.02] Symmetries
<---> [02.03] RL shells
<---> [02.04] K-grid lattice
<---> [02.05] Energies [ev] & Occupations
<---> [WARNING]Metallic system
<---> [03] Transferred momenta grid
<---> [03.01] Main loop
<---> [WARNING] The system is a metal but Drude term not included.
<---> [WARNING] Missing non-local pseudopotential contribution
<---> [04] Bethe-Salpeter Kernel
<---> [05] BSE solver(s)
<---> [05.01] Diagonalization solver
<---> BSK res epsilon | | [000%] --(E) --(X)
<---> P01: BSK res epsilon |####################| [100%] --(E) --(X)
<---> [06] Game Over & Game summary

[Daniele Varsano]

Dear Zhou,

can not generate the needed variable (bss) by using "yambo -o b -y d", while " yambo -y d " can achieve.

I do suspect that there is something confusing. Which version of yambo are you using. If you are using the new version the command lines
are changed. Please have a look here

what's more, the Gvectors in the exchange part is still 15 when I use variable ALLGexx, why?

Don't know, try to delete your calculated databases and recalculate it. Have you used the MaxGvecs somewhere?

This is strange, if the problem persist, please post input/report file and output of the yamo -D.

How to do a efficient convergence for NGsBlkXs? I mean, do convergence by seting NGsBlkXs "20, 50, 80,110,140" or "100, 200, 300, 400", or "200, 400, 600," .... What's the rough rule for such test? Same with the MaxGvecs. Maybe this problem looks a bit naive but frustrated me for a long time.

This is something that is really system dependent!! Find your strategy.
But, why do you want to change the MaxGvecs? This limit the calculation of further calculation and it is the maximum of G-vectors you can use in all the runlevel. You can setup once for all in the initialization to speed up the calculation in the case you are sure you do not need more than MaxGvec in all the variable. If the Gvec are not too much, as in the case of localized sysytems with big vacuum region, I would not touch this variable.

Best,

Daniele

[ljzhou86]

I use the latest version of yambo.3.4.0
I can not generate the needed variable (bss) by using "yambo -o b -y d", these related file of input/report file and output of the yamo -D in the attachment.

Still for the variable NGsBlkXs, we take the case of Si_wire in tutorial for example, the valule in 05_W is 100, If I want to do a convergence, I may set NGsBlkXs "20, 50, 80,110,140" or "100, 200, 300, 400" or "100 500 1000 2000"? how to control the scale of variation in general? In the description of this variable :"A smaller number with respect to FFTGvecs is generally needed to correctly describe the LF effects ". For the FFTGvecs, it is noted "A reduction is suggested with respect to the Number of plane waves in the DFT-KS calculation". which variable mean the Number of plane waves in the DFT-KS calculation? Is it MaxGvecs?

The reason for me to change the MaxGvecs is based on this description for it "It can be also reduced to speed all yambo calculations as the FFT dimension will be decide on the basis of the highes closed shell." I note that the MaxGvecs used in these cases of tutorial are usually smaller than the value I generate by "yambo -i -V RL". while, as you state above, it is not need to change it?

After I have done some calcuation, I found the value of MaxGvecs have a little influence on the final absorption, why? Thank you.

[Daniele Varsano]

Dear Zhou,

I use the latest version of yambo.3.4.0

so you should use the "New" command lines for the BSE.
yambo -k sex
PLease have a look to the yambo web page.
Anyway please note that your yambo-o-yd file contains and IP calculations so you cannot setup any Gvectors for the exchange and correlations, and no diagonalization is needed.

If I want to do a convergence, I may set NGsBlkXs

As I told you beore, this depend on your system!! You cannot say before, as in all convergence studies, vary this variable until
the result does not change anymore up to accuracy you need. NgsBlkXs=20,100,500,1000,2000 could help you to have an idea.
MaxGvecs you can change it in the setup runlevel, and this will be the maximum number of Gvec you can use in all the runlevels, this is not the value of Gvecs in a specific runlevels. All the Gvec entering in a calculation "NgsBlkXs", "ExxRLvcs" etc. cannot be bigger that this value.
In general you can set this value to the Gvec of the wavefunctions which is lower than the Gevec used for the density in a DFT calculations. Next you can play with the FFTGvecs. If you do not specify this variable you will have FFTGves=MaxGves, but in general you can reduce this value to speed up you calculations. When reducing it , take a look to the report if the orthonormalization of our wfs is satisfied to some extent.

Number of plane waves in the DFT-KS calculation? Is it MaxGvecs?

Yes, as stated above you can reduce this at the beginning, setup runlevel, or mantain a big number and reduce it reducing FFTGvecs.

I note that the MaxGvecs used in these cases of tutorial are usually smaller than the value I generate by "yambo -i -V RL". while, as you state above, it is not need to change it?

As stated above, you can reduce it to speed up the calculations, as not all Gvec used for the density in the DFT are needed, anyway please consider that the tutorials are made to teach yambo at schools and are meant to run in few minutes on a laptop, so usually they are out of convergence.

I found the value of MaxGvecs have a little influence on the final absorption, why

Because this is the number of Gvec stored in the databse and not the Gvec entering in you particular runlevel. Changing it you are only changing the values of FFTGvecs which is equal of MaxGvecs if not specified. If the MaxGvecs are enough to mantin orthonormalization this does not affect much the quality of the calculation.

Hope it helps,

Daniele