[Pw_forum] DOS of graphene

[Elie Moujaes]

Dear Alexandra,

 

my sampling included 210 points. I will be checking the program again and see what went wrong. Than you

 

Elie

 

Elie Moujaes 
 University of Nottingham
 NG7 2RD

 UK



 
> Date: Wed, 10 Mar 2010 07:07:32 +0100
> From: alexandra.carvalho at epfl.ch
> To: pw_forum at pwscf.org
> Subject: Re: [Pw_forum] DOS of graphene
> 
> Dear Elie,
> 
> The Fermi level in graphene converges very slowly with the k-point 
> sampling. Did you check the result with a very large number of k-points?
> 
> Alexandra
> 
> -----------------------------------------------------------
> Alexandra Carvalho,
> Ceramics Laboratory
> Swiss Federal Institute of Technology of Lausanne (EPFL)
> 
> 
> Quoting Giovanni Cantele <giovanni.cantele at na.infn.it>:
> 
> >> Dear all,
> >> I have plotted the density of states of graphene but when I looked at the
> >> graph, DOS was not zero at the fermi level (I got it to be -0.988 eV). my
> >> Programm seems pretty fine and i have checked it several times but with in
> >> vain..You will find attached the ps version and the input for the dos.x
> >> command...
> >> Regards
> >> Elie Moujaes
> >> University of Nottingham
> >> NG7 2RD
> >> UK
> >
> > The problem that the Fermi level is not at the energy you expect might not
> > be related to a mistake. The zero energy is not well defined in a
> > plane-wave calculation (try to browse the forum, there should be more than
> > one topic about that!). One should compute the DOS, then calculate the
> > Fermi energy (as the energy at which the integrated DOS matches the number
> > of the electrons), then for the sake of clarity you can shift you DOS (or
> > band structure) plot so as the Fermi energy is at 0.
> >
> > However, this might not be the problem in you calculation.
> > I'm not very sure that your calculation is right, because the shape of
> > your DOS plot does not look like the one of graphene. So the first problem
> > to solve is to understand on the top of which scf / nscf calculation you
> > have built your DOS plot. Unless I missed something, there are not
> > sufficient elements to understand what happened.
> >
> > Giovanni
> >
> > --
> > Giovanni Cantele, PhD
> > CNR-SPIN and Dipartimento di Scienze Fisiche
> > Universita' di Napoli "Federico II"
> > Complesso Universitario M. S. Angelo - Ed. 6
> > Via Cintia, I-80126, Napoli, Italy
> > Phone: +39 081 676910 - Fax: +39 081 676346
> > Skype contact: giocan74
> >
> > ResearcherID: http://www.researcherid.com/rid/A-1951-2009
> > Web page: http://people.na.infn.it/~cantele
> > http://www.nanomat.unina.it
> >
> > _______________________________________________
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> >
> 
> 
> 
> -- 
> 
> Alexandra Carvalho,
> Ceramics Laboratory
> Swiss Federal Institute of Technology of Lausanne (EPFL)
> 
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