[Pw_forum] Iron cluster relaxation

[Axel Kohlmeyer]

On Fri, 10 Nov 2006, Konstantin Kudin wrote:

kostya,

KK>  It is not clear why the job should have a hard crash like this instead
KK> of either terminating gracefully, recovering from the condition in some
KK> way, or at least printing the very thing that you say, i.e. that
KK> "optimization terminated due to noise in the forces, increase cutoff",
KK> or something else similar.

i agree. after this issue has come up quite a few times 
in the last months, it may be worth putting in the effort
and changing the code, so that it a) exits gracefully,
b) has a few more options on how to handle the resets,
e.g. force a minimum number of steps between two resets,
or have a small(!) randomization of coordinates.

that just leaves the usual problem: who is going to do it?
anybody in the market for making a lot of people happy?

KK>  Actually, in my experience just restarting the job with the last
KK> coordinates has a very good chance to advance further, and even find a
KK> lower energy structure since the BFGS will be started from scratch.

hmmm. if you see the latter, then perhaps the reset is not
a complete reset and there may be a bug (unless you have
a 'randomization' of the coordinates due to limited
accuracy when reading in the so far optimized coordinates).

cheers,
   axel.

KK> 
KK>  Kostya
KK> 
KK> 
KK> 
KK> --- Axel Kohlmeyer <akohlmey at cmm.chem.upenn.edu> wrote:
KK> 
KK> > On Fri, 10 Nov 2006, Cyrille Barreteau wrote:
KK> > 
KK> > CB> Dear Pwscf users
KK> > 
KK> > dear cyrille,
KK> > 
KK> > did you check the mailing list archives?
KK> > 
KK> > IIRC, this error seems to happen if you try to
KK> > optimize the geometry too tightly for the
KK> > given convergence of the wavefunction or
KK> > when you suffer from 'ripples' due to a
KK> > too small density cutoff.
KK> > 
KK> > salut,
KK> >   axel.
KK> > 
KK> > CB> I am trying to relax an iron cluster (cubocathedron) and
KK> > CB> pw.x systematicaly ends with the following error:
KK> > CB> 
KK> > CB> 
KK> >
KK> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
KK> > CB>      from bfgs : error #         1
KK> > CB>      bfgs history already reset at previous step
KK> > CB> 
KK> >
KK> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
KK> > CB> 
KK> > CB>      stopping ...
KK> > CB> 2
KK> > CB> 
KK> > CB> 
KK> > CB> You can find the input and output files on the following web
KK> > site:
KK> > CB> 
KK> > CB>
KK> >
KK> http://www-drecam.cea.fr/Images/Pisp/cbarreteau/temporaire/cuboctahedron_relax.in
KK> > CB>
KK> >
KK> http://www-drecam.cea.fr/Images/Pisp/cbarreteau/temporaire/cuboctahedron_relax.out
KK> > CB> 
KK> > CB> 
KK> > CB> thanks in advance for any constructive comment :-)
KK> > CB> 
KK> > CB>    cyrille
KK> > CB> 
KK> > CB> 
KK> > 
KK> > -- 
KK> >
KK> =======================================================================
KK> > Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu  
KK> > http://www.cmm.upenn.edu
KK> >    Center for Molecular Modeling   --   University of Pennsylvania
KK> > Department of Chemistry, 231 S.34th Street, Philadelphia, PA
KK> > 19104-6323
KK> > tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel:
KK> > 1-215-898-5425
KK> >
KK> =======================================================================
KK> > If you make something idiot-proof, the universe creates a better
KK> > idiot.
KK> > 
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KK> > 
KK> 
KK> 
KK> 
KK>  
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-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.