[Pw_forum] relaxation of the 60 C atom supercell

[mohnish pandey]

Dear Ellie,

For phonon calculation you definitely need to converge forces and
energy to much accuracy. First check the convergence for these two for
relax calculation then do phonon calculation.

On Mon, Sep 12, 2011 at 2:50 AM, Elie Moujaes
<elie.moujaes at hotmail.co.uk> wrote:
> Dear all,
> I am still "fighting" with the 60 carbon atom system that I am trying to
> relax. I did a relaxation using 4 k-points and I got the system relaxed then
> I did an scf calculation with 25 points (for phonon calculations) and the
> total force is 0.099839. Does this mean that using 4 points is not enough?
> how many points do I have to consider as 25 points would really take a lot
> of time? Shall I relax for 10 k-points, the same as I was doing for an scf
> calculation? Can anyone advise me on that?
> Thanks again and sorry to disturb you with that many times. I am trying to
> avoid the negative frequencies that I obtained before totally relaxing the
> crystal.
>
> Elie M
> University of Nott
> ng7 2rd
> uk
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>



-- 
Regards,
MOHNISH,
-----------------------------------------------------------------
Mohnish Pandey
BTech-Mtech, IIT Kanpur
Senior Project Associate,
Department of Chemical Engineering,
IIT KANPUR, UP, INDIA
-----------------------------------------------------------------