[Pw_forum] Vc-relax again
Paolo Giannozzi
paolo.giannozzi at uniud.it
Sun Mar 30 21:41:34 CEST 2014
On Sat, 2014-03-29 at 20:26 +0300, Elio Physics wrote:
> Professor Paolo G. gave me a link for this problem.. I understood
> that I need to increase the cutoff kinetic energy
did you also understand that you need first of all to check that the
two systems you are comparing are the same?
> which I did and I realized that the pressure goes down but to -6;
> however the total force is still 0.4!
>
>
> (1) Anyone knows how to solve this problem.
>
>
> I have run the calculation again wih ibrav=0 instead of ibrav=6 and
> the crystal axes were:
>
>
> a(1) = ( 0.492694 0.853319 0.000001 )
> a(2) = ( 0.492685 -0.853314 -0.000001 )
> a(3) = ( 0.000001 0.000004 4.274389 )
>
>
> The pressure was -0.02 and the total force was 0.001 which was fine in
> both scf and vc-relax. However when I redid an scf calculation with
> ibrav=6 with c/a =4.274389 (which I read from the ibrav=0 calculation
> with the same atomic positions of the "ibrav=0" calculation), I still
> got P =-16 and total force=0.4. I was trying to convert the ibrav=0
> input to ibrav=6..did I do anything wrong?
>
>
>
>
> Any help would be appreciated
>
>
> Thanks
>
>
> Elio Nahdan
>
>
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--
Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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