[Pw_forum] graphene scf calculation

[Derek Stewart]

Hi Koroteev,

Just to follow up on some of the other suggestions, I would encourage you to use a very fine k-point grid in the graphene plane.  For spare k-point meshes in the graphene plane, the calculated density of states will actually have a small band gap (which shouldn't occur in graphene).  This probably won't affect your scf convergence, but it will be important for calculated physical properties.

Best regards,

Derek
  



################################
Derek Stewart, Ph. D.
Scientific Computation Associate
** New Webpage **
http://sites.google.com/site/dft4nano/
250 Duffield Hall
Cornell Nanoscale Facility (CNF)
Ithaca, NY 14853
stewart (at) cnf.cornell.edu
(607) 255-2856

----- Original Message -----
From: Vit [mailto:vitruss at gmail.com]
To: pw_forum at pwscf.org
Sent: Wed, 11 Nov 2009 15:42:13 +0600
Subject: [Pw_forum] graphene scf calculation

Dear all!
I'm trying to plot graphene band structure as a part of computations of  
carbon based composites. But scf calculation for graphene can't achieve  
convergence. I've tried different mixing_beta, mixing_mode, degaus ant  
ecutwfc. The example input file is attached. Could you please tell me  
which parameters I should tune to achieve convergence?

Thanks in advance,
Koroteev Victor
PhD student,
Nikolaev Institute of Inorganic Chemistry SB RAS
Novosibirsk, Russian Federation.