[Pw_forum] Graphene structure

[Ettore Baldini Neto]

Thanks a lot Hande and Gabriele,

best regards,

Ettore

On Nov 22, 2010, at 11:23 AM, Hande Ustunel wrote:

> Dear Ettore,
> 
> As with any structure including metals, you would need some sort of
> smearing.
> 
> Try something like
> 
>    occupations='smearing'
>    smearing='mv'
>    degauss=0.01
> 
> in the &system portion of your input. You must however be informed about
> the usage of smearing since the number of k-points that will be sufficient
> for convergence will be degauss-dependent. I would read the papers refered
> to in the Doc/INPUT_PW.txt. As a rule of thumb soemthing like 0.01 or 0.02
> are good smearing widths. 
> 
> Incidentally, our vacuum is a tad too large. This will ill-condition your
> problem (and consequently mess up your convergence) as well as increase the
> run-time. I would decrease it to something like 15 A.
> 
> If these fail (which I doubt they will in your case) you can try one of the
> following remedies which sometimes work :
> 
> 1) Increase number of kpoints.
> 2) Change the location of Ti slightly.
> 3) Change pseudo (if you can) 
> 4) Change mixing mode and mixing beta.
> 
> Hope this helps,
> Hande
> 
> 
> On Mon, 22 Nov 2010, Ettore Baldini Neto wrote:
> 
>> Dear QE users,
>> 
>> I'm kinda new with quantum espresso. I'm trying to relax a Graphene structure with  32C atoms plus one Ti atom at a given position and the structure do not converge.
>> In what follows I copy the input. Could anyone give-me some hint? Is there anything wrong or that can be improved? I'm using the pp's from the QE data base. I'm planning to generate my own pp's soon.
>> I'm using a k-point grid of 6x6x1 since with SIESTA (dzp basis) the energy and force convergence is achieved without problem.
>> 
>> With best regards,
>> 
>> ************************************************************
>> Dr. Ettore Baldini-Neto
>> Wernher von Braun Center for Advanced Research
>> Campinas, Brazil.
>> ************************************************************
> 
> -- 
> Hande Toffoli
> Department of Physics
> Office 439
> Middle East Technical University
> Ankara 06531, Turkey
> Tel : +90 312 210 3264
> http://www.physics.metu.edu.tr/~hande
> 
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum