[ERROR]Impossible to define an appropriate parallel structur

[Longjun Xiang]

Dear developers:

I am following this tutorial you presented to repeat the BSE calculation of bulk hBN. I got the wrong signal when I perform the convergence test for variable BSEBands. I pick three valence bands [6,7,8] and three conduction bands [9,10,11] to test the variables. All combination is OK but the [8]-[9] cannot be calculated correctly. The wrong message is:

[ERROR] STOP signal received while in :[04] Response Functions in Transition space
[ERROR]Impossible to define an appropriate parallel structure

Input file for 7-9 (run correctly):
#
# ooooo oooo .. ooo ooo ooooooooo. .oooo.
# `88. .8" .88. `88. .88 `88" `Y8b dP" `Yb
# `88. .8" .8"88. 888b d"88 88 888 88 88
# `88.8" .8" `88. 8 Y88. .P 88 88oooo888" 88 88
# `88" .88ooo888. 8 `888" 88 88 `88b 88 88
# 88 .8" `88. 8 Y 88 88 .88P `8b d8"
# o88o88o 888o8 88 o88bood8P" `Ybod8P"
#
#
# GPL Version 4.2.3 Revision 127. (Based on r.14793 h.bfefd4
# MPI+SLK Build
# http://www.yambo-code.org
#
optics # [R OPT] Optics
bss # [R BSS] Bethe Salpeter Equation solver
bse # [R BSE] Bethe Salpeter Equation.
bsk # [R BSK] Bethe Salpeter Equation kernel
BSEmod= "retarded" # [BSE] resonant/retarded/coupling
BSKmod= "SEX" # [BSE] IP/Hartree/HF/ALDA/SEX
BSSmod= "d" # [BSS] (h)aydock/(d)iagonalization/(i)nversion/(t)ddft`
BSENGexx=20 Ry # [BSK] Exchange components
BSENGBlk=3 Ry # [BSK] Screened interaction block size
#WehCpl # [BSK] eh interaction included also in coupling
KfnQPdb= "none" # [EXTQP BSK BSS] Database
KfnQP_N= 1 # [EXTQP BSK BSS] Interpolation neighbours
% KfnQP_E
1.440000 | 1.000000 | 1.000000 | # [EXTQP BSK BSS] E parameters (c/v) eV|adim|adim
%
KfnQP_Z= ( 1.000000 , 0.000000 ) # [EXTQP BSK BSS] Z factor (c/v)
KfnQP_Wv_E= 0.000000 eV # [EXTQP BSK BSS] W Energy reference (valence)
% KfnQP_Wv
0.00 | 0.00 | 0.00 | # [EXTQP BSK BSS] W parameters (valence) eV| 1|eV^-1
%
KfnQP_Wv_dos= 0.000000 eV # [EXTQP BSK BSS] W dos pre-factor (valence)
KfnQP_Wc_E= 0.000000 eV # [EXTQP BSK BSS] W Energy reference (conduction)
% KfnQP_Wc
0.00 | 0.00 | 0.00 | # [EXTQP BSK BSS] W parameters (conduction) eV| 1 |eV^-1
%
KfnQP_Wc_dos= 0.000000 eV # [EXTQP BSK BSS] W dos pre-factor (conduction)
% BEnRange
2.00000 | 10.00000 | eV # [BSS] Energy range
%
% BDmRange
0.10000 | 0.10000 | eV # [BSS] Damping range
%
BEnSteps= 100 # [BSS] Energy steps
% BLongDir
1.000000 | 1.000000 | 0.000000 | # [BSS] [cc] Electric Field
%
% BSEBands
7 | 9 | # [BSK] Bands range
%

Input file for 8-9 (can not run correctly):
#
# ooooo oooo .. ooo ooo ooooooooo. .oooo.
# `88. .8" .88. `88. .88 `88" `Y8b dP" `Yb
# `88. .8" .8"88. 888b d"88 88 888 88 88
# `88.8" .8" `88. 8 Y88. .P 88 88oooo888" 88 88
# `88" .88ooo888. 8 `888" 88 88 `88b 88 88
# 88 .8" `88. 8 Y 88 88 .88P `8b d8"
# o88o88o 888o8 88 o88bood8P" `Ybod8P"
#
#
# GPL Version 4.2.3 Revision 127. (Based on r.14793 h.bfefd4
# MPI+SLK Build
# http://www.yambo-code.org
#
optics # [R OPT] Optics
bss # [R BSS] Bethe Salpeter Equation solver
bse # [R BSE] Bethe Salpeter Equation.
bsk # [R BSK] Bethe Salpeter Equation kernel
BSEmod= "retarded" # [BSE] resonant/retarded/coupling
BSKmod= "SEX" # [BSE] IP/Hartree/HF/ALDA/SEX
BSSmod= "d" # [BSS] (h)aydock/(d)iagonalization/(i)nversion/(t)ddft`
BSENGexx=20 Ry # [BSK] Exchange components
BSENGBlk=3 Ry # [BSK] Screened interaction block size
#WehCpl # [BSK] eh interaction included also in coupling
KfnQPdb= "none" # [EXTQP BSK BSS] Database
KfnQP_N= 1 # [EXTQP BSK BSS] Interpolation neighbours
% KfnQP_E
1.440000 | 1.000000 | 1.000000 | # [EXTQP BSK BSS] E parameters (c/v) eV|adim|adim
%
KfnQP_Z= ( 1.000000 , 0.000000 ) # [EXTQP BSK BSS] Z factor (c/v)
KfnQP_Wv_E= 0.000000 eV # [EXTQP BSK BSS] W Energy reference (valence)
% KfnQP_Wv
0.00 | 0.00 | 0.00 | # [EXTQP BSK BSS] W parameters (valence) eV| 1|eV^-1
%
KfnQP_Wv_dos= 0.000000 eV # [EXTQP BSK BSS] W dos pre-factor (valence)
KfnQP_Wc_E= 0.000000 eV # [EXTQP BSK BSS] W Energy reference (conduction)
% KfnQP_Wc
0.00 | 0.00 | 0.00 | # [EXTQP BSK BSS] W parameters (conduction) eV| 1 |eV^-1
%
KfnQP_Wc_dos= 0.000000 eV # [EXTQP BSK BSS] W dos pre-factor (conduction)
% BEnRange
2.00000 | 10.00000 | eV # [BSS] Energy range
%
% BDmRange
0.10000 | 0.10000 | eV # [BSS] Damping range
%
BEnSteps= 100 # [BSS] Energy steps
% BLongDir
1.000000 | 1.000000 | 0.000000 | # [BSS] [cc] Electric Field
%
% BSEBands
8 | 9 | # [BSK] Bands range
%

The results for all other combination have been attached in [spectrum.pdf]. For completeness, I have also attached the wrong report file.

How can I fix this problem?

Thanks in advance.

[Daniele Varsano]

Dear Longjun Xiang,
the problem is probably due to the fact you have fewer blocks than cpus.
Note that you have not specified your parallelization strategy and the default configuration get confused in case you have just one transition for each k point.
You can either try to reduce the number of cpus, or define by hands the parallelization strategy (verbosity -V par) by
BS_CPU= "12 1 1" # [PARALLEL] CPUs for each role
BS_ROLEs= "k eh t" # [PARALLEL] CPUs roles (k,eh,t)

Note you have only 14 kpts so you cannot assign a number of cpu larger than that.
For a description of the parallelization strategy in Yambo in the BSE you can have a look here:
https://iopscience.iop.org/article/10.1 ... 48X/ab15d0
Section 8.5


Best,
Daniele

[Longjun Xiang]

Ok, the problem is solved. Actually, I have read roughly the ARXIV version of this attached paper. Anyway, I will take more time to read it. Many thanks.