[Wien] Force on frozen atoms in a MSR1a

[Laurence Marks]

N.B., the only time it would make sense is if you are calculating something
like an activation energy barrier, in which case just do "touch .stop".

Fixing atoms, for instance of a substrate, is bad physics in my opinion.

______________________________
Laurence Marks
Dept Mat Sci & Eng
Northwestern University
www.numis.northwestern.edu
847 491 3996
On May 13, 2014 9:47 AM, "Laurence Marks" <L-marks at northwestern.edu> wrote:

> I assume by "frozen atoms" you mean. ones where you forced via
> case.inM there to be no movement. This make no sense in MSR1a.
>
> No sense.
>
> Contrary to what people think, it does NOT improve the convergence to
> fix the positions of certain atoms, and I consider it to be
> inappropriate physics. The reason is that the convergence of MSR1a
> depends upon the number of clusters of eigenvalues the combined
> density-atoms problem, not on the number of atoms. Indeed, this is
> also true of PORT and other methods such as conjugant gradients. Alas,
> the unpublished literature in DFT (and other fields) gets this wrong.
>
> N.B., if instead by "frozen atoms" you mean ones which have via
> symmetry no forces, this is different and indicates that there is
> something wrong with your structure.
>
> On Tue, May 13, 2014 at 9:36 AM, Salman Zarrini
> <salman.zarrini at tu-darmstadt.de> wrote:
> > ++++++++++++++++++++++++++++++++++++++++++++++++
> > Dear Wien2k user,
> >
> > All the convergence criteria including energy, charge and total force
> > on all the free atoms have already met their thresholds in my MSR1a
> > calculation, however, the total force on all the frozen atoms are far
> > away from the force convergence threshold, and so, the job is still
> > running. So, I was wondering if the frozen atoms are included from
> > force convergence in a MSR1a minimization? If so, is there any way to
> > exclude frozen atoms and if does it make sense?
> >
> > Cheers,
> >
> > Salman Zarrini
> > ++++++++++++++++++++++++++++++++++++++++++++++++
> >
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>
>
> --
> Professor Laurence Marks
> Department of Materials Science and Engineering
> Northwestern University
> www.numis.northwestern.edu 1-847-491-3996
> Co-Editor, Acta Cryst A
> "Research is to see what everybody else has seen, and to think what
> nobody else has thought"
> Albert Szent-Gyorgi
>
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