GW band gap same with PBE

[burkzdemir]

Dear Yambo developers,

I runned GW calculation and obtained interpolated the bands. However, I found band gap same with PBE band gap. What could be the problem?

[Daniele Varsano]

Dear Burak,
it is not easy to guess what the problem could be with such few information.
It is possible that for some reason the QP energies are not taken into account which is obtained by inserting this variable in the ypp.in file:

Code: Select all

 GfnQPdb= "E < SAVE/ndb.QP"

If you have redirected the ndb.QP file in a directory different from the SAVE directory you need to set the path of that directory in the above variable set.
If this is not the problem, please post your input, QP report and standard output of the ypp run.
Best,
Daniele

[burkzdemir]

Ok, it worked but now I am getting an error message: "Not enough states to converge the Fermi Level"

[Daniele Varsano]

Dear Burak,
as I wrote before, it is hard to help you if you do not provide information.
If you post the report file of the GW calculation and the ypp input file we can have an idea of what is going on.
are you dealing with a metallic system?

Daniele

[burkzdemir]

System is not metallic. yambo.in and ypp.in are as follows.

yambo.in:

#
# /$$ /$$ /$$$$$$ /$$ /$$ /$$$$$$$ /$$$$$$
# | $$ /$$//$$__ $$| $$$ /$$$| $$__ $$ /$$__ $$
# \ $$ /$$/| $$ \ $$| $$$$ /$$$$| $$ \ $$| $$ \ $$
# \ $$$$/ | $$$$$$$$| $$ $$/$$ $$| $$$$$$$ | $$ | $$
# \ $$/ | $$__ $$| $$ $$$| $$| $$__ $$| $$ | $$
# | $$ | $$ | $$| $$\ $ | $$| $$ \ $$| $$ | $$
# | $$ | $$ | $$| $$ \/ | $$| $$$$$$$/| $$$$$$/
# |__/ |__/ |__/|__/ |__/|_______/ \______/
#
# GPL Version 4.3.1 Revision 132. (Based on r.15642 h.de46b6
# MPI Build
# http://www.yambo-code.org
#
ppa # [R Xp] Plasmon Pole Approximation
gw0 # [R GW] GoWo Quasiparticle energy levels
HF_and_locXC # [R XX] Hartree-Fock Self-energy and Vxc
em1d # [R Xd] Dynamical Inverse Dielectric Matrix
EXXRLvcs= 18094 RL # [XX] Exchange RL components
Chimod= "" # [X] IP/Hartree/ALDA/LRC/PF/BSfxc
% BndsRnXp
1 | 30 | # [Xp] Polarization function bands
%
NGsBlkXp= 1 RL # [Xp] Response block size
% LongDrXp
1.000000 | 0.000000 | 0.000000 | # [Xp] [cc] Electric Field
%
PPAPntXp= 27.21138 eV # [Xp] PPA imaginary energy
% GbndRnge
15 | 25 | # [GW] G[W] bands range
%
GDamping= 0.10000 eV # [GW] G[W] damping
dScStep= 0.10000 eV # [GW] Energy step to evaluate Z factors
DysSolver= "n" # [GW] Dyson Equation solver ("n","s","g")
%QPkrange # [GW] QP generalized Kpoint/Band indices
1|10| 15| 25|

---------------------------------------------------------------------------------------
ypp.in:

#
#
# Y88b / e e e 888~~\ ,88~-_
# Y88b / d8b d8b d8b 888 | d888 \
# Y88b/ /Y88b d888bdY88b 888 _/ 88888 |
# Y8Y / Y88b / Y88Y Y888b 888 \ 88888 |
# Y /____Y88b / YY Y888b 888 | Y888 /
# / / Y88b / Y888b 888__/ `88_-~
#
#
# GPL Version 4.3.1 Revision 132. (Based on r.15642 h.de46b6
# MPI Build
# http://www.yambo-code.org
#
electrons # [R] Electrons (and holes)
bnds # [R] Bands
cooIn= "rlu" # Points coordinates (in) cc/rlu/iku/alat
% DOSERange
1.000000 |-1.000000 | eV # Energy range
%
DOSESteps= 500 # Energy steps
DOS_broad= 0.10000 eV # Broadening of the DOS
% INTERP_Grid
-1 |-1 |-1 | # Interpolation BZ Grid
%
INTERP_Shell_Fac= 20.00000 # The bigger it is a higher number of shells is used
CIRCUIT_E_DB_path= "none" # SAVE obtained from the QE `bands` run (alternative to %BANDS_kpts)
BANDS_path= "" # BANDS path points labels (G,M,K,L...)
BANDS_steps=100 # Number of divisions
% BANDS_bands
15 | 25 | # Number of bands
%
#BANDS_built_in # Print the bands of the generating points of the circuit using the nearest internal point
%BANDS_kpts # K points of the bands circuit
0.00000 | 0.00000 | 0.00000 |
0.5|0|0|
0.5|-0.5|0|
0|-0.5|0|
0|0|0|
0|0|0.5|
0.49996|0|0.5|
0.49996|-0.49835|0.51099|
0|-0.49835|0.51099|
0|0|0.5|
%
GfnQPdb= "E < SAVE/ndb.QP"
%

[Daniele Varsano]

Dear Burak,
the report file is always useful to understand what is going on,
anyway frmo your input file I an see an extra % at the end of the file:

Code: Select all

GfnQPdb= "E < SAVE/ndb.QP"
%

this may cause confusion!
while there is a missing % at the end of the yambo.in file, but this may be a problem of the copy/pate?

Best,
Daniele

[burkzdemir]

Dear Daniele,

I removed the extra % at the end of the ypp.in but the problem persists. I could not attach the report file because it says file extension is not allowed. I tried zipping but this time it complained about the size of the file. I tried to copy the ingredients of the report file and this time it complained about the number of characters.

[Daniele Varsano]

Dear Burak,
you can rename the report file with a .txt suffix, then it should not complain. Please post also the standard output of the ypp run.
Best,
Daniele

[Daniele Varsano]

Dear Burak,
even if most probably unrelated with your problem,
please also note that your GW calculations are totally under convergence wrt the dimension of the screening matrix:

Code: Select all

NGsBlkXp= 1 RL

and probably also wrt the number of bands included in the response function. This can also lead to unphysical corrections of the QP energies, but again
probably this is probably unrelated to the problem you are facing.
Best,
Daniele

[burkzdemir]

Following is the ypp output.

<---> [01] CPU structure, Files & I/O Directories
<---> [02] Y(ambo) P(ost)/(re) P(rocessor)
<---> [03] Core DB
<---> :: Electrons : 40.00000
<---> :: Temperature [ev]: 0.000000
<---> :: Lattice factors [a.u.]: 6.24251 8.62769 21.56526
<---> :: K points : 1296
<---> :: Bands : 30
<---> :: Symmetries : 1
<---> :: RL vectors : 180945
<---> [04] K-point grid
<---> :: Q-points (IBZ): 1296
<---> :: X K-points (IBZ): 1296
<---> [05] CORE Variables Setup
<---> [05.01] Unit cells
<---> [05.02] Symmetries
<---> [WARNING]Spatial Inversion not found among the given symmetry list
<---> [05.03] RL shells
<---> [05.04] K-grid lattice
<01s> [05.05] Energies [ev] & Occupations
<01s> [06] Interpolation tool
<01s> [06.01] Loading special Points for the Unknown lattice
<01s> [WARNING]Unknown lattice unit cell
<01s> [06.02] External/Internal QP corrections
<01s> E<SAVE/ndb.QP[ E-E PPA: 27.21138 XG: 1 Xb: 1 30 Scb: 15 25]
<01s> [QP_ctl (Nearest K-pt)] Kpts covered exactly [o/o]: 0.771605
<01s> [QP_ctl (Nearest K-pt)] Nighbours : 1
<01s> [QP_ctl (Nearest K-pt)] Kpts covered [o/o]: 99.22839

[ERROR] STOP signal received while in :[06.02] External/Internal QP corrections
[ERROR]Not enough states to converge the Fermi Level