Hi Michael,

    Thanks for your comments. You may be right. I haven't relaxed lateral
lattice parameters, just used the experimental values. 

Best regards,
Fhokrul

 

________________________________________
From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Michael Sluydts 
[michael.sluy...@ugent.be]
Sent: Tuesday, December 22, 2015 11:10 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

While I haven't done any graphene calculations, one of the typical
issues in bandgap discrepancies is also the existence of strain. Ensure
your lateral lattice parameters are optimized using your current
functional so that you're certain you are looking at the band structure
of the energetic minimum. Of course don't optimize the vacuum or you'll
end up with graphite...

Best regards,

Michael Sluydts

Op 22/12/2015 om 17:43 schreef Islam, Md F:
> Thanks, for your reply. I have used a vacuum of 30 bohr but I can
> try with larger vacuum to check if it makes any difference.
>
>
> Fhokrul
>
>
> ________________________________________
> From: wien-boun...@zeus.theochem.tuwien.ac.at 
> [wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of 
> t...@theochem.tuwien.ac.at [t...@theochem.tuwien.ac.at]
> Sent: Tuesday, December 22, 2015 10:20 AM
> To: A Mailing list for WIEN2k users
> Subject: Re: [Wien] Graphene bandstructure
>
> Hi,
>
> For graphene, you need to add vacuum in the z-direction in order to
> avoid interactions between the periodically repeated monolayers.
> Maybe the vacuum that you used is not large enough.
>
> F. Tran
>
> On Tue, 22 Dec 2015, Islam, Md F wrote:
>
>> 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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--
ir. Michael Sluydts
Center for Molecular Modeling
Ghent University
Technologiepark 903
9052 Zwijnaarde, Belgium
tel. +32 (0)9 264 66 19
https://molmod.ugent.be

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