gap's problem

Concerns issues with computing quasiparticle corrections to the DFT eigenvalues - i.e., the self-energy within the GW approximation (-g n), or considering the Hartree-Fock exchange only (-x)

Moderators: Daniele Varsano, andrea.ferretti, andrea marini, myrta gruning

gap's problem

Postby fatimazahra » Mon Jun 15, 2015 11:13 am

Hi everyone
I have a system with odd number of electrons, I have ran calculation with quantum espresso, I got that the system is a semiconductor with a band gap (1.20 eV), when I run with yambo, the system is metal, and I get this message in r-setup:

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

Fermi Level [ev]:-3.386976
Electronic Temp. [ev K]: 0.2585E-1 300.0
Bosonic Temp. [ev K]: 0.2585E-1 300.0
El. density [cm-3]: 0.812E+23
States summary : Full Metallic Empty
0001-0007 0008-0008 0009-0024

[WARNING]Metallic system
N of el / N of met el: 15.00000 0.98075
Average metallic occ.: 0.980745
X BZ K-points : 100
Fatima Ezzahra Ramadan
PhD student
LPHE-Simulation-Modeling,Université Mohammed 5 Agdal Rabat Morocco
f.ramadan88@gmail.com
fatimazahra
 
Posts: 52
Joined: Mon Oct 28, 2013 10:15 am

Re: gap's problem

Postby Daniele Varsano » Mon Jun 15, 2015 11:20 am

Dear Fatima,
Most probably this is due to the electronic temperature (did you use any smearing in the qe run?).
You can anyway avoid this problem by redoing the setup by setting:
Code: Select all
ElecTemp=0

in your input file (remove first the ndb.* datatbase calculated previously).

In any case please provide your QE output and complete yambo report and we will have a look.
Next: the initialization subforum is more appropriate than the self-energy section.

Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/
User avatar
Daniele Varsano
 
Posts: 2058
Joined: Tue Mar 17, 2009 2:23 pm

Re: gap's problem

Postby fatimazahra » Wed Jun 17, 2015 12:33 pm

Hi Daniele
yes, I need to use smearing in QE calculation,
I redid the setup with ElecTemp=0, but I didn't avoid my problem,
Fatima Ezzahra Ramadan
PhD student
LPHE-Simulation-Modeling,Université Mohammed 5 Agdal Rabat Morocco
f.ramadan88@gmail.com
fatimazahra
 
Posts: 52
Joined: Mon Oct 28, 2013 10:15 am

Re: gap's problem

Postby Daniele Varsano » Wed Jun 17, 2015 1:54 pm

Dear Fatima,
this is rather strange. Could you please post the complete yambo report and qe output?
Best,

Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/
User avatar
Daniele Varsano
 
Posts: 2058
Joined: Tue Mar 17, 2009 2:23 pm

Re: gap's problem

Postby Zahra Taghipour » Wed Sep 16, 2015 5:41 pm

Dear Developers,

I intend to use GW correction on DFT bandgap of my sample. The material that I am working on is a semiconductor with band gap as small as 0.1 meV!
Due to convergency issue, I have to use Smearing. But, this led yambo to see my material as metaic!

In order to test different parameters, I switched to the well-known and simpler case of GaSb! The PP that I have been using are GA.PBE-D-MT_FHI.UPF, and SB.PBE-MT_FHI.UPF. However, even in the case of GaSb, and without using Smearing, I get BG=0! And again, Yambo sees it as metalic and after a long calculation of GW, I get the same corrections on both CB and VB, at gamma point (The gap at gamma point is supposed to be around 0.8 meV).

I already tried to set the ElecTemp equal to zero. But it did not help!
I have attached the result of QE and Yambo for GaSb.

I would appreciate if you could help me resolve this issue.

Thanks,
Zahra Taghipour,
PhD student,
University of New Mexico, USA
You do not have the required permissions to view the files attached to this post.
Zahra Taghipour
 
Posts: 23
Joined: Mon Aug 17, 2015 5:56 am

Re: gap's problem

Postby Daniele Varsano » Wed Sep 16, 2015 5:55 pm

Dear Zahra,
from what I can see, the QE ground state calculation gives you:
Code: Select all
 highest occupied, lowest unoccupied level (ev):     6.5346    6.5346

ie, a metallic beahvour or at least a gap smaller then 0.1meV.

For what concern the yambo setup (and GW calculations), the electronic temperature it is not set to zero:
r_setup:
Code: Select all
 .-Input file : (none)
 | ElecTemp=0.1000E-3     eV    # Electronic Temperature
 | BoseTemp=0.1000E-3     eV    # Bosonic Temperature


o-PP_181Ry-nbnd300.qp
Code: Select all
# | gw0                          # [R GW] GoWo Quasiparticle energy levels
# | ElecTemp=0.1000E-3     eV    # Electronic Temperature
# | BoseTemp=0.1000E-3     eV    # Bosonic Temperature
# | FFTGvecs=  5817        RL    # [FFT] Plane-waves


Please be sure you are running the right input file!!

Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/
User avatar
Daniele Varsano
 
Posts: 2058
Joined: Tue Mar 17, 2009 2:23 pm

Re: gap's problem

Postby Zahra Taghipour » Thu Sep 17, 2015 1:46 am

Dear Daniele,

I have tried to set the ElectTemp to zero as follow:

Running: yambo -i -V gen -F 00init.in
-> this already shows ElectTemp=0!!!

Running yambo -F 00init.in
-> This reads 00init.in as input and gives r_setup as output, however, this shows:
{ Electronic Temp. [ev K]: 0.1000E-3 1.160 }

Other than this, I do not know how I am supposed to change the ElectTemp to zero! Please help me to resolve this issue. It has been a while that I am struggling with it without any result! :cry:

Attached, are 00init.in and r-setup files, if needed!

Zahra,
PhD student,
UNM, USA
You do not have the required permissions to view the files attached to this post.
Zahra Taghipour
 
Posts: 23
Joined: Mon Aug 17, 2015 5:56 am

Re: gap's problem

Postby Daniele Varsano » Thu Sep 17, 2015 9:39 am

Dear Zahra,
ok the problem here is that the QE ground state calculation outcome is a metallic system.
Even if you put a zero temperature, yambo cannot converge the Fermi level and need to add an electronic temperature to do that.
If you think that this is an artifact, you should try to get a non-metallic behavior from the qe calculations, for instance you can try to add unoccupied states in the scf calculation and work with "fixed" occupations, or you can ask suggestions to the pw_forum.

Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/
User avatar
Daniele Varsano
 
Posts: 2058
Joined: Tue Mar 17, 2009 2:23 pm

Re: gap's problem

Postby kerensanni » Tue Nov 13, 2018 1:02 pm

Hi everyone
I have a system with odd number of electrons, I have ran calculation with quantum espresso, I got that the system is a semiconductor with a band gap (1.84 eV), when I run with yambo, the system is metal.
I changed the Electemp to 0. Is still the same issue. I had to use smearing in my quantum espresso calculation because of the Manganese in my system. Pls what should I do.

Thanks,

Nagura Jonah,
Undergraduate student,
Department of Physics,
University of Ibadan.
kerensanni
 
Posts: 2
Joined: Sat Nov 10, 2018 12:49 am

Re: gap's problem

Postby Daniele Varsano » Tue Nov 13, 2018 1:38 pm

Dear Jonah,
please post your setup report file together with quantum espresso input and output.

Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/
User avatar
Daniele Varsano
 
Posts: 2058
Joined: Tue Mar 17, 2009 2:23 pm

Next

Return to Self-Energy

Who is online

Users browsing this forum: No registered users and 1 guest

cron