[Pw_forum] -Image error

[Nicola Marzari]

On 16/10/2016 09:32, Alwaleed Ahmed Adllan ahmed Abusin wrote:
> Dear ALL
>
> /I'm trying to do phonon calculation for graphene monolayer
> /
>
> /with high q-point and kpoint 30x30x30 and 60x60x60 respectively
> /


You really need to work on the fundamental of electronic structure
before starting a calculations, and/or look at papers that have
done this before. you'd understand why it might be more relevant
to use a mesh that has no sampling in the perpendicular direction,
and much fewer k and q points - I'd start with 4x4x1 and 8x8x1 respectively
(the number of calculations you have to do is linearly proportional to the
number of q points, and the cost of each is proportional to the k-points -
your suggested meshes would make each calculation 3375 times more
expensive, and you'd need to do 1687 times more calculations - so overall
570,000 times more expensive.

I.e. if my suggestion takes a day, your suggestion will take 1561 years.


				nicola



-- 
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Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
Director, National Centre for Competence in Research NCCR MARVEL, EPFL
http://theossrv1.epfl.ch/Main/Contact http://nccr-marvel.ch/en/project