[Pw_forum] Strained Graphene Nanoribbon

[Ricardo Faccio]

Hi
The number of k points is always chosen in terms of convergence of some
physical property, this is the final decision. Dependent of the metallic
nature of your case, you may choose high or lower number of k-points.
In the case of codes with not so efficient methods for Brillouin Zone
integration, e.g. SIESTA, you need to use a considerable amount of
k-points in order to reach convergence.
But in QE, you can get the best choice, going step by step, increase
little by little, the number of k-pints, until reaching convergence.
Certainly, you will get a number considerably lower than 100.
Additionally, H-saturated zigzag nanoribbons are insulators -
antiferromagnets, so maybe you will need few kpoints.
Regards
Ricardo

> Hi Arles,
>
> Sorry, I realized the same, the reason I chose 1 1 100 was, I was using
> another quantum software and the forum there had displayed results with
> having the k points as 100, so to be in better position to be able to
> compare with their result I chose 100, but as you have pointed out and I
> learned myself, the decision was indeed insane. I am still trying to learn
> how specifically can one decide on k points, do you have any suggestion on
> k
> points for my input file,
>
> On Thu, May 12, 2011 at 10:11 AM, Arles V. Gil Rebaza
> <arvifis at gmail.com>wrote:
>
>> Why do you choose  1 1 100  k-points.... this is an insane
>> desicion....!!!!!!
>>
>> PhD std. Arles V. Gil Rebaza
>> Instituto de Física de La Plata
>> La Plata - Argentina
>>
>>
>>
>>
>>
>> 2011/5/12 swapnil chandratre <swapnil.chandratre at gmail.com>
>>
>>> Hi,
>>>
>>> Thank you for sparing time on this, I will try to get it resolved
>>> sooner.
>>> Any suggestions are heartily welcomed.
>>>
>>>
>>> On Thu, May 12, 2011 at 9:03 AM, Paolo Giannozzi
>>> <giannozz at democritos.it>wrote:
>>>
>>>>
>>>> On May 12, 2011, at 15:49 , swapnil chandratre wrote:
>>>>
>>>> >  I just wanted to know if there is no error with the script
>>>>
>>>> I don't know if there is an error in the script. I just tried to
>>>> run it on a PC, it starts but it is definitely too large for a
>>>> single CPU. Since the code writes > 800Mb Kohn-Sham
>>>> wavefunctions for each of the 100 k-points, insufficient disk
>>>> space looks like a promising explanation
>>>>
>>>> P.
>>>> ---
>>>> Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
>>>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
>>>> Phone +39-0432-558216, fax +39-0432-558222
>>>>
>>>>
>>>>
>>>>
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>>>
>>>
>>>
>>> --
>>> Regards,
>>> Swapnil Chandratre
>>> Graduate Student
>>> Dept. of Mechanical Engineering,
>>> University of Houston,
>>> Houston, TX
>>> (M)-713-294-9546
>>>
>>> _______________________________________________
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>>>
>>
>>
>> --
>> ###--------->   Arles V.   <---------###
>>
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>>
>
>
> --
> Regards,
> Swapnil Chandratre
> Graduate Student
> Dept. of Mechanical Engineering,
> University of Houston,
> Houston, TX
> (M)-713-294-9546
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>


-- 
-------------------------------------------------
  Dr. Ricardo Faccio
  Prof. Adjunto de Física
  Mail: Cryssmat-Lab., Cátedra de Física, DETEMA
  Facultad de Química, Universidad de la República
       Av. Gral. Flores 2124, C.C. 1157
       C.P. 11800, Montevideo, Uruguay.
  E-mail: rfaccio at fq.edu.uy
  Phone: 598 2 924 98 59
         598 2 929 06 48
  Fax:   598 2 9241906
  Web:  http://cryssmat.fq.edu.uy/ricardo/ricardo.htm