Thank you for your previous help. I have some more silly questions about running BSE with Yambo code. I try calculate absorption spectrum of 2D MoS2. The SCF calculation is done by QE with the primer cell (only one MoS2) with 24*24*1 K-mesh. There are 26 electrons included in the SCF, no SOC. In all Yambo calculations, I always use 4 Nodes with 192 cores. In the static screening calculation, I only include 4000 G-vectors.If I use 6000 G-vectors, the calculation job will crash due to insufficient virtural memory. In BSE kernel and diago solver, as you can see, I only specify BSENGexx= 2000 RL and BSENGBlk= 400 RL. It seems to take 12 hours to finish the job.

My question is how to estimate the number of G-vectors used in the exchange components and block size? What is the threthold that it is enough to cut-off at spcific number, 4000 or 5000? Thank you.

The r_setup file is attached in the attachment.

The yambo input files are listed as below:

01_2D_BSE_screening

Code: Select all

```
# Version 5.2.1 Revision 22792 Hash (prev commit) ace55e496e
# Branch is
# MPI+HDF5_MPI_IO Build
# http://www.yambo-code.org
#
screen # [R] Inverse Dielectric/Response Matrix
em1s # [R][Xs] Statically Screened Interaction
rim_cut # [R] Coulomb potential
dipoles # [R] Oscillator strenghts (or dipoles)
RandQpts=1000000 # [RIM] Number of random q-points in the BZ
RandGvec= 100 RL # [RIM] Coulomb interaction RS components
CUTGeo= "slab z" # [CUT] Coulomb Cutoff geometry: box/cylinder/sphere/ws/slab X/Y/Z/XY..
% CUTBox
0.000000 | 0.000000 | 0.000000 | # [CUT] [au] Box sides
%
CUTRadius= 0.000000 # [CUT] [au] Sphere/Cylinder radius
CUTCylLen= 0.000000 # [CUT] [au] Cylinder length
CUTwsGvec= 0.700000 # [CUT] WS cutoff: number of G to be modified
Chimod= "HARTREE" # [X] IP/Hartree/ALDA/LRC/PF/BSfxc
% BndsRnXs
10 | 25 | # [Xs] Polarization function bands
%
NGsBlkXs= 4000 RL # [Xs] Response block size
% LongDrXs
1.000000 | 1.000000 | 1.000000 | # [Xs] [cc] Electric Field
%
```

Code: Select all

```
# Version 5.2.1 Revision 22792 Hash (prev commit) ace55e496e
# Branch is
# MPI+HDF5_MPI_IO Build
# http://www.yambo-code.org
#
optics # [R] Linear Response optical properties
rim_cut # [R] Coulomb potential
bse # [R][BSE] Bethe Salpeter Equation.
dipoles # [R] Oscillator strenghts (or dipoles)
RandQpts= 1000000 # [RIM] Number of random q-points in the BZ
RandGvec= 100 RL # [RIM] Coulomb interaction RS components
CUTGeo= "slab z" # [CUT] Coulomb Cutoff geometry: box/cylinder/sphere/ws/slab X/Y/Z/XY..
% CUTBox
0.000000 | 0.000000 | 0.000000 | # [CUT] [au] Box sides
%
CUTRadius= 0.000000 # [CUT] [au] Sphere/Cylinder radius
CUTCylLen= 0.000000 # [CUT] [au] Cylinder length
CUTwsGvec= 0.700000 # [CUT] WS cutoff: number of G to be modified
BSKmod= "SEX" # [BSE] IP/Hartree/HF/ALDA/SEX/BSfxc
BSEmod= "resonant" # [BSE] resonant/retarded/coupling
BSENGexx= 2000 RL # [BSK] Exchange components
BSENGBlk= 400 RL # [BSK] Screened interaction block size [if -1 uses all the G-vectors of W(q,G,Gp)]
#WehCpl # [BSK] eh interaction included also in coupling
% BSEQptR
1 | 1 | # [BSK] Transferred momenta range
%
% BSEBands
10 | 25 | # [BSK] Bands range
%
```

Code: Select all

```
bss # [R] BSE solver
rim_cut # [R] Coulomb potential
optics # [R] Linear Response optical properties
dipoles # [R] Oscillator strenghts (or dipoles)
bse # [R][BSE] Bethe Salpeter Equation.
RandQpts= 1000000 # [RIM] Number of random q-points in the BZ
RandGvec= 101 RL # [RIM] Coulomb interaction RS components
CUTGeo= "slab z" # [CUT] Coulomb Cutoff geometry: box/cylinder/sphere/ws/slab X/Y/Z/XY..
% CUTBox
0.000000 | 0.000000 | 0.000000 | # [CUT] [au] Box sides
%
CUTRadius= 0.000000 # [CUT] [au] Sphere/Cylinder radius
CUTCylLen= 0.000000 # [CUT] [au] Cylinder length
CUTwsGvec= 0.700000 # [CUT] WS cutoff: number of G to be modified
BSKmod= "SEX" # [BSE] IP/Hartree/HF/ALDA/SEX/BSfxc
BSEmod= "resonant" # [BSE] resonant/retarded/coupling
BSSmod= "d" # [BSS] (h)aydock/(d)iagonalization/(s)lepc/(i)nversion/(t)ddft`
BSENGexx= 2015 RL # [BSK] Exchange components
BSENGBlk= 403 RL # [BSK] Screened interaction block size [if -1 uses all the G-vectors of W(q,G,Gp)]
#WehCpl # [BSK] eh interaction included also in coupling
KfnQPdb= "E < ../G0W0_nospinpol2/2D_G0W0/ndb.QP" # [EXTQP BSK BSS] Database action
KfnQP_INTERP_NN= 1 # [EXTQP BSK BSS] Interpolation neighbours (NN mode)
KfnQP_INTERP_shells= 20.00000 # [EXTQP BSK BSS] Interpolation shells (BOLTZ mode)
KfnQP_DbGd_INTERP_mode= "NN" # [EXTQP BSK BSS] Interpolation DbGd mode
% KfnQP_E
0.000000 | 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
0.000000 | 0.000000 | 0.000000 | # [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
0.000000 | 0.000000 | 0.000000 | # [EXTQP BSK BSS] W parameters (conduction) eV| 1 |eV^-1
%
KfnQP_Wc_dos= 0.000000 eV # [EXTQP BSK BSS] W dos pre-factor (conduction)
% BSEQptR
1 | 1 | # [BSK] Transferred momenta range
%
% BSEBands
10 | 25 | # [BSK] Bands range
%
% BEnRange
2.00000 | 8.00000 | eV # [BSS] Energy range
%
% BDmRange
0.100000 | 0.100000 | eV # [BSS] Damping range
%
BEnSteps= 100 # [BSS] Energy steps
% BLongDir
1.000000 | 1.000000 | 1.000000 | # [BSS] [cc] Electric Field
%
BSEprop= "abs" # [BSS] Can be any among abs/jdos/kerr/magn/dich/photolum/esrt
BSEdips= "none" # [BSS] Can be "trace/none" or "xy/xz/yz" to define off-diagonal rotation plane
WRbsWF # [BSS] Write to disk excitonic the WFs
```