Metallic system

Concerns any physical issues arising during the setup step (-i option). This includes problems with symmetries, k/q-point sets, and so on. For technical problems (running in parallel, etc), refer to the Technical forum.

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lamia
Posts: 68
Joined: Mon Dec 05, 2016 5:09 pm

Metallic system

Post by lamia » Fri May 28, 2021 1:01 am

Dear developers,

I am trying to use Yambo in order to improve the DFT's band gap of my system.
I have this problem that Yambo sees my system as Metallic, while the band gap is 0.4 eV.

[WARNING]Metallic system

How could I get band gap correction when Yambo sees my system as metallic?!
Taouil Lamia
University of Mohammed V
Faculty of science - Rabat
Morocco

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Daniele Varsano
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Re: Metallic system

Post by Daniele Varsano » Fri May 28, 2021 9:17 am

Dear Lamia,

the system is seen as metallic by yambo or it is already metallic in the QE ground state calculation?
If it is not the case, can you post your QE output and r_setup?

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/

lamia
Posts: 68
Joined: Mon Dec 05, 2016 5:09 pm

Re: Metallic system

Post by lamia » Fri May 28, 2021 3:52 pm

Dear Daniele,

Thank you for your reply.
The attached is the output and r_setup files.

Best,

Lamia
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Taouil Lamia
University of Mohammed V
Faculty of science - Rabat
Morocco

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Daniele Varsano
Posts: 3773
Joined: Tue Mar 17, 2009 2:23 pm
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Re: Metallic system

Post by Daniele Varsano » Fri May 28, 2021 4:17 pm

Dear Lamia,

some suggestions:
if the system is a semiconductor, try to run QE using the occupation fixed (no smearing).
Next, yambo cannot perform a GW calculation not because of the metallicity but because you have a non-uniform grid:

Code: Select all

[WARNING][RL indx] 2 equivalent points in the rlu grid found

 [RL indx] X grid is not uniform. Gamma point only.
 [WR./SAVE//ndb.kindx]---------------------------------------
  Fragmentation                    :no
  Polarization last K   :  90
  QP states             :   1   90
  X grid is uniform     :no
  BS scattering         :no
  COLL scattering       :no
In order to overcame this problem first have a look to the QE messages:

Code: Select all

Message from routine setup:
     no reason to have ecutrho>4*ecutwfc
     Message from routine setup:
     using ibrav=0 with symmetry is DISCOURAGED, use correct ibrav instead
Try to use the correct ibrav.

If this not solve the problem in the yambo setup, you can add this flag in the yambo setup input:

Code: Select all

NoDiagSC
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/

lamia
Posts: 68
Joined: Mon Dec 05, 2016 5:09 pm

Re: Metallic system

Post by lamia » Sun May 30, 2021 7:08 pm

Dear Daniele,

The system that I'm working on is a semiconductor. It doesn't work even with the suggestions. Any other solutions, please ?




Best,

Lamia
Taouil Lamia
University of Mohammed V
Faculty of science - Rabat
Morocco

User avatar
Daniele Varsano
Posts: 3773
Joined: Tue Mar 17, 2009 2:23 pm
Contact:

Re: Metallic system

Post by Daniele Varsano » Mon May 31, 2021 8:06 am

Dear Lamia,

I think you should solve first the problem of the non-uniform k point grid.
This should be achieved by defining an appropriate ibrav and an automatic k point sampling (possibly centred at gamma, which is not now the case).

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/

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