[Pw_forum] DOS of graphene

[alexandra.carvalho at epfl.ch]

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)