[Pw_forum] DOS of graphene

[Paolo Giannozzi]

It has been explaned many times (but apparently not too many) that
absolute values of Kohn-Sham energies are arbitrary. The zero of 
the energy in a DOS plot is also arbitrary and is usually set to 
a convenient place, typically: top of the valence band, or bottom 
of the conduction band, or the Fermi energy. For graphene the 
obvious choice is at the "Dirac point" (which should, for pure
graphene and well-converged calculations, coincide with the Fermi 
energy)

P.

On Thu, 2013-12-05 at 00:05 +0330, ehsan targholi wrote:
> Dear Dr Paulatto
> thanks for your reply , if may for you please explain more.
> this attach file show difference in my obtained DOS and reported DOS
> in article.
> 
> 
> 
> 
> 
> 
> best regard
> ehsan targholi 
> graduate student of chemistry department of iust  
> 
> 
> On Wed, Dec 4, 2013 at 4:28 PM, Lorenzo Paulatto
> <lorenzo.paulatto at impmc.upmc.fr> wrote:
>         
>         On 12/03/2013 09:11 PM, ehsan targholi wrote:
>         
>                 i calculate DOS of graphene but my DOS is not
>                 compatible with reference.
>                 in the reference, DOS of graphene is U-shaped with
>                 minimum at 0 eV but
>                 in my calculation this minimum occure at -.35 eV.  i
>                 increase K-point to
>                 48 48 1 and change pseudopotentials. but result not
>                 change.
>                 DOS of my calculation is attached,
>                 
>         
>         
>         
>         
>         Dear Ehsan,
>         the DOS should be zero at the Fermi energy, not at zero. What
>         is the Fermi energy in your calcualtion (is is printedi n teh
>         output file). It is customary torecenter the X axis of the DOS
>         plot in order to Have E_Fermi=0, but it is nto automatic.
>         
>         cheers
>         
>         _______________________________________________
>         Pw_forum mailing list
>         Pw_forum at pwscf.org
>         http://pwscf.org/mailman/listinfo/pw_forum
> 
> 
-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222