[Pw_forum] Question about Young's modulus

[Mahdi Mirnezhad]

Dear Developers,
I think there is a problem in the calculation of stress in Quantum
Esperesso. This problem concern with the volume of unit cell. For bulk
structures there is no problem for determination of Volume but in the
super cell method code calculate stress according to unit cell volume
so when i calculate Young's Modulus for graphene with two method
(strees/strain or (E=(1/V)*second derivative of energy) ) i get
different answer.
What is your suggestion?
Thanks for your reply.

Mahdi  Mirnezhad
Msc student of Mechanics
Guilan University.



On 10/7/10, Mahdi Mirnezhad <mirnezhad.mm at gmail.com> wrote:
> Dear all,
> I calculated Young's modulusfor graphene and i got correct answer but
> when I want to calculate Young's modulus for CNT(3,3) for a axial
> strain with the same condition (same PS) i got a wrong answer?
> Any suggestion appreciated,
> tanks
>
> mahdi mirnezhade
>