[Pw_forum] graphene's band gap

[Mehmet Topsakal]

Dear Eric,

In addition, if you select 18x18x1 kpoints, your mesh should include both K
and M points.

But for a band-structure calculation, you should arrange a kpoints list
along special directions, such as from GAMMA-to-M-to-K-to-GAMMA, and do a
nscf calculation....



On Wed, Mar 9, 2011 at 11:28 AM, xirainbow <nkxirainbow at gmail.com> wrote:

> Dear Eric:
> The occupied and unoccupied bands touch each other only at M point(or K
> point, I forget it).
> You must include this point in you k-mesh.
> Furthermore, if you include spin-orbital coupling, the band gap will be
> opened at this point.
>
> On Thu, Mar 10, 2011 at 1:30 AM, Eric Germaneau <germaneau at gucas.ac.cn>wrote:
>
>>  Dear all,
>>
>> I'm trying to compute graphene's band gap but get stuck.
>> From my understanding a scf calculation should provide the same energy for
>> the highest occupied and lowest occupied level which means a zero gap.
>> I played with the number a kpoints a finally got a band gap of 0.57 which
>> is not null.
>> The scf convergence looks good.
>> I'm not (yet) an expert in DFT calculation so may did something wrong or
>> misunderstood something here.
>> So, I wonder if someone has already successfully performed such
>> calculation.
>> I have attached my input file.
>> Thanks in advance,
>>
>>                                 Eric.
>>
>> --
>>  * Be the change you wish to see in the world
>> *  — Mahatma Gandhi —
>>
>> Dr. Éric Germaneau <germaneau at gucas.ac.cn>
>>
>> College of Physical Sciences
>> Graduate University of Chinese Academy of Sciences
>> Yuquan Road 19A
>> Beijing 100049
>> China
>>
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>>
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>
>
> --
> ____________________________________
> Hui Wang
> School of physics, Fudan University, Shanghai, China
>
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-- 

Mehmet Topsakal  (Ph.D. Student)
UNAM-Institute of Materials Science and Nanotechnology.
Bilkent University. 06800 Bilkent, Ankara/Turkey
Tel: 0090 312 290 3527 ; Fax: 0090 312 266 4365
http://www.researcherid.com/rid/A-5015-2010
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