[Wannier] bands structure of graphene

Nicola Marzari nicola.marzari at epfl.ch
Mon May 14 11:41:17 CEST 2012

Dear Hua-Qing, Julen,

actually missing the K-point shouldn't give rise to any problem.
I attach a few slides for a metallic carbon nanotube, but the concept
is the same:

first slide: use a frozen window below the first green line
(the states you want to keep) and a disentanglement window just above
the top of the pi/pi^star manifold (the second green line). This would 
give you very good p_z states on every carbon, and bonds on, well, ever 
bond (so 2.5 WFs per carbon atom)

second slide: This shows that missing the crossing point does not have
any effect.

third slide: this is how band structures should be reproduced (red -
full pwscf calculation; black - wannier interpolation, done using the 
k-points denoted by the blue lines).


On 14/05/2012 11:14, Julen Ibanez Azpiroz wrote:
> Dear Huaqing,
> Have you explicitly included the K point where the Dirac cone is
> expected in the original k-point mesh in the .win file? If not, you may
> be getting an interpolation error between k-points nearby K that leads
> to the gap. You could try to use a 3*3*3 grid or so in the .win file
> that includes the K point explicitly and see if you get degenerate bands
> at K.
> best regards
> --
> ========================================
> Julen Ibañez Azpiroz
> Materia Kondentsatuaren Fisika Saila
> Zientzia eta Teknologia Fakultatea
> Euskal Herriko Unibertsitatea
> ========================================
> _______________________________________________
> Wannier mailing list
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Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
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