Dear friends,
Recently, I encounter an error while testing the BSE spectrum of graphene---“[ERROR]Fractional e/h occupations found. BS coupling forced.”
I searched this forum and found a former discussion on this issue (viewtopic.php?f=13&t=195). However, that discussion focused mainly on the physics of exciton and the cause of this issue was not mentioned. Though the exciton effect is inessential in bulk metals, it counts in some low-dimensional metallic systems, such as carbon nanotubes [PRL 92, 07742 (2004)].
Would you please explain the cause of such error and is it possible for Yambo to deal with excitonic effects of metallic system?
Sincerely,
Can Yambo deal with the BSE of metallic systems?
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Can Yambo deal with the BSE of metallic systems?
Guangfu Luo
Institute for Molecular Science
National Institutes of Natural Sciences, Japan
Institute for Molecular Science
National Institutes of Natural Sciences, Japan
- claudio
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Re: Can Yambo deal with the BSE of metallic systems?
Dear Guangfu Luo
if you have a semimetal like graphene (or nanotubes) you can choose a k-point sampling
that does not contain the metalic k-points.
For example in graphene any k-point sampling that is not divisible by 3 like 2x2x1 4x4x1,....., 100x100x1
and then calculate the normal Bethe-Salpeter using these samplings.
For example have a look to the papers:
Ab initio high-energy excitonic effects in graphite and graphene
Paolo E. Trevisanutto, Markus Holzmann, Michel Côté, and Valerio Olevano
Phys. Rev. B 81, 121405(R) (2010)
and
Excitonic Effects on the Optical Response of Graphene and Bilayer Graphene
Li Yang, Jack Deslippe, Cheol-Hwan Park, Marvin L. Cohen, and Steven G. Louie
Phys. Rev. Lett. 103, 186802 (2009)
Claudio
if you have a semimetal like graphene (or nanotubes) you can choose a k-point sampling
that does not contain the metalic k-points.
For example in graphene any k-point sampling that is not divisible by 3 like 2x2x1 4x4x1,....., 100x100x1
and then calculate the normal Bethe-Salpeter using these samplings.
For example have a look to the papers:
Ab initio high-energy excitonic effects in graphite and graphene
Paolo E. Trevisanutto, Markus Holzmann, Michel Côté, and Valerio Olevano
Phys. Rev. B 81, 121405(R) (2010)
and
Excitonic Effects on the Optical Response of Graphene and Bilayer Graphene
Li Yang, Jack Deslippe, Cheol-Hwan Park, Marvin L. Cohen, and Steven G. Louie
Phys. Rev. Lett. 103, 186802 (2009)
Claudio
Claudio Attaccalite
[CNRS/ Aix-Marseille Université/ CINaM laborarory / TSN department
Campus de Luminy – Case 913
13288 MARSEILLE Cedex 09
web site: http://www.attaccalite.com
[CNRS/ Aix-Marseille Université/ CINaM laborarory / TSN department
Campus de Luminy – Case 913
13288 MARSEILLE Cedex 09
web site: http://www.attaccalite.com
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- Posts: 17
- Joined: Mon Dec 14, 2009 10:46 am
Re: Can Yambo deal with the BSE of metallic systems?
Dear Claudio,
Thanks for your help; I got the point. (This trick is also used in the Raman spectrum calculation of graphene)
Sincerely,
Thanks for your help; I got the point. (This trick is also used in the Raman spectrum calculation of graphene)
Sincerely,
Guangfu Luo
Institute for Molecular Science
National Institutes of Natural Sciences, Japan
Institute for Molecular Science
National Institutes of Natural Sciences, Japan