[Pw_forum] vc-relax bug?

[Javier Antonio Montoya]

Thanks a lot.

On 4/5/07, cesards at msi.umn.edu <cesards at msi.umn.edu> wrote:
>
> Hi Javier,
>
> After your first cell optimization, try starting again from scratch
> using the final configuration of the previous calculation. If the problem
> persists, increase the cutoff energies.
>
> Good luck.
>
> Cesar R.S. da Silva
>
> >
> > Message: 10
> > Date: Wed, 4 Apr 2007 17:31:23 +0200
> > From: "Javier Antonio Montoya" <j.antonio.montoya at gmail.com>
> > To: pw_forum at pwscf.org
> > Subject: [Pw_forum] vc-relax bug?
> > Reply-To: pw_forum at pwscf.org
> >
> > ------=_Part_26133_24163750.1175700683893
> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> > Content-Transfer-Encoding: 7bit
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> >
> > Hello dear all,
> >
> > In recent days I have been trying to get a triclinic cell to have a
> > diagonal
> > stress by using vc-relax. The pw.x program reads data in the correct
> way,
> > calculates the right starting volume for the cell given as input and
> also
> > seems to do right the first electronic minimization but, as soon as the
> > Wentzcovitch Damped Cell-Dynamics Minimization starts, it gives cell
> > parameters and ion positions that are not consistent with the energies
> and
> > stress that it prints (i.e. if you take those cells and ions to an
> > independent scf run the final energy and stress differ from the ones in
> > the
> > vc-output) the problem is that in the end, when I get a nice diagonal
> > stress
> > after 60 or more dynamic steps, the difference between the reported
> energy
> > in the vc-output and the energy of the system that you get with the cell
> > and
> > ion parameters shown is of almost 1 Ry and the pressures differ by more
> > than
> > 10GPa. Any idea? by the way the ph.x complain and doesn't get anything
> > from
> > such restart files.
> > The output files are huge for sending by e-mail because my system is 72
> > atoms big, but I can provide them.
> >
> > cheers,
> >
> > JAvier.
> >
>
>
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