[Pw_forum] pressure derivative of elastic constant

[Bipul Rakshit]

Dear Stefano,
Thanks for yr kind reply. For calculating the elastic constant i am refering
the following paper.

 S K R Patil et. al Phys. Rev. B *73*, 104118 (2006).

So in this paper, they generally fit a parabola equation in terms of energy
as a function of strain and thus finds the C11, C12 and C44 etc.
But as u suggested to find the C11 etc at different volume, but change in
volume cause the change in pressure. So the minimum of the parabola is not
minimum at high pressure.


So i need an equation like Murnaghan equation of state, in which the the
pressure derivative is included.



On Tue, Jun 22, 2010 at 4:32 PM, Stefano Baroni <baroni at sissa.it> wrote:

> 1) Calculate C11, C12, and C44 for different volumes
> 2) Calculate numerically their volume derivatives
> 3) Use the chain rule to express the pressure derivatives in terms of the
> volume derivatives
> hope this helps - Stefano B
>
> On Jun 22, 2010, at 11:39 AM, Bipul Rakshit wrote:
>
> Dear PWSCF user,
> I want to calculate the pressure derivative of elastic constant for some of
> my cubic materials (ScP, ScN in NaCl phase). Please anybody tell me the
> procedure or refer any paper, where i get the method of calculating the
> pressure derivative of elastic constants (C11, C12, C44)
>
>
> regards
>
> --
> Bipul Rakshit
> Research Fellow,
> S N Bose Centre for Basic Sciences,
> Salt Lake,
> Kolkata 700 098
> India
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> ---
> Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center - Trieste
> http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) /
> stefanobaroni (skype)
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-- 
Dr. Bipul Rakshit
Research Associate,
S N Bose Centre for Basic Sciences,
Salt Lake,
Kolkata 700 098
India
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