[Pw_forum] Iron cluster relaxation

[Konstantin Kudin]

 Axel,

 While your explanation is technically correct, it does not really
address the underlying issue :-)

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

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

 Kostya



--- Axel Kohlmeyer <akohlmey at cmm.chem.upenn.edu> wrote:

> On Fri, 10 Nov 2006, Cyrille Barreteau wrote:
> 
> CB> Dear Pwscf users
> 
> dear cyrille,
> 
> did you check the mailing list archives?
> 
> IIRC, this error seems to happen if you try to
> optimize the geometry too tightly for the
> given convergence of the wavefunction or
> when you suffer from 'ripples' due to a
> too small density cutoff.
> 
> salut,
>   axel.
> 
> CB> I am trying to relax an iron cluster (cubocathedron) and
> CB> pw.x systematicaly ends with the following error:
> CB> 
> CB> 
>
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> CB>      from bfgs : error #         1
> CB>      bfgs history already reset at previous step
> CB> 
>
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> CB> 
> CB>      stopping ...
> CB> 2
> CB> 
> CB> 
> CB> You can find the input and output files on the following web
> site:
> CB> 
> CB>
>
http://www-drecam.cea.fr/Images/Pisp/cbarreteau/temporaire/cuboctahedron_relax.in
> CB>
>
http://www-drecam.cea.fr/Images/Pisp/cbarreteau/temporaire/cuboctahedron_relax.out
> CB> 
> CB> 
> CB> thanks in advance for any constructive comment :-)
> CB> 
> CB>    cyrille
> CB> 
> CB> 
> 
> -- 
>
=======================================================================
> 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.
> 
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