[Pw_forum] about elastic constant

[Bipul Rakshit]

Dear Michael Mehl,
I have read the two papers
http://cst-www.nrl.navy.mil/users/mehl/papers/cij453.pdf

and

Phys. Rev. B 47, 2493 (1993)
,
But my question is, they have given only two equation, and our unknown
quantity are 3 (C11, C12, and C44). So can we find three unknown quantity
from two equations acuratelly.



On Thu, Jul 16, 2009 at 10:27 PM, Michael Mehl <rcjhawk at gmail.com> wrote:

> Bipul Rakshit wrote:
>
> > Because in order to calculate 3 elastic constants (C11, C12 and C44) we
> > require 3 equations, so do I have to use the above three equations, both
> > type (volume conservative and non-conservative) to calculate a single
> > set of elastic constants?
>
> Yes.
>
> >
> > please guide me for the same.
>
> You'll have to compute the bulk modulus at same volume that you use to
> compute C44 and C11-C12.  In a cubic system B = (C11+2 C12)/3, giving
> you enough information to get all three elastic constants at that volume.
>
> There are many, many programs that will compute B(V), see this list's
> archives for details.
>
> My favorite reviews of the subject are:
>
> http://cst-www.nrl.navy.mil/users/mehl/papers/cij453.pdf
>
> and
>
> Phys. Rev. B 47, 2493 (1993)
>
> but I may be somewhat biased.
>
> --
> Michael J. Mehl, Naval Research Laboratory, Washington DC
> On Sabbatical at Duke University until 31 July 2009
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>



-- 
Bipul Rakshit
PhD Student,
Barkatullah University,
Bhopal 462026,
MP, India
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20090716/dc26a60f/attachment.html>