[Wien] Graphene bandstructure

[Islam, Md F]

Hi Prof Blaha,

    I have got the gap from plotting bandstructure as well as DOS calculations.
I can see the linear dispersion at the K point just like the way it is suppose to be
when I plot all the bands in eV range. But if I zoom in at the K point in meV range,
I can see the gap.  

   I don't think there is anything wrong with the structure. I did check all bond lengths,
angles before I ran the calculations and they are correct. I suspect I may have to adjust 
parameters. I started to see some difference with LDA xc functional with larger k mesh.


Thanks,
Fhokrul  
 



________________________________________
From: wien-bounces at zeus.theochem.tuwien.ac.at [wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha [pblaha at theochem.tuwien.ac.at]
Sent: Tuesday, December 22, 2015 11:35 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

Graphene is metallic by "symmetry", i.e. EF is at a 2-fold eigenvalue at
the K-point and bands cross with a linear dispersion.

 From where do you know that graphene has a gap in your calculations ??

 From :gap in the scf file or from plotting the bandstructure or ...

It the state at K is not degenerate, you have the wrong symmetry and are
not doing graphene.

Am 22.12.2015 um 16:51 schrieb Islam, Md F:
> Hi,
>
>       I am trying to do a bandstructure calculation of graphene to check if I can
> reproduce results discussed in literature (I am using a unit cell of 2 atoms).
> With spin-orbit coupling, there should be a gap of the order of few micro-eV
> and without spin-orbit, there should not be any gap at Dirac point. But I am
> getting a gap of meV even without spin-orbit. I tried both GGA and LDA with
> very dense mesh but the gap does not close. So I am wondering if anyone
> have any suggestion about how to do it in Wien2k.
>
>
> Thanks,
> Fhokrul
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