Re: [ESPResSo] Addendum: Bug in Lennard-Jones interaction in ESPResSo versions 2.1.1u up to 2.1.2d

[Tristan Bereau]

Dear all,

I believe I am responsible for this bug. I do try to be as careful as  
possible when submitting to the CVS but this was obviously not enough  
this time, and I would like to send my deepest apologies to the  
ESPResSo community. I learn from my mistakes, and hope you will  
forgive my lack of experience.

Very best,

Tristan



On Mar 10, 2009, at 12:15 PM, Torsten Stuehn wrote:

> Dear all,
>
> here are some details, that will help you to find out if you were  
> affected by the bug:
>
> * if you had only one short range non bonded lennard-jones  
> interaction e.g.:
>
>      inter $type_1 $type_2 lennard-jones $eps $sig $rcut $shift  
> $offset $cap_radius $min_radius
>      , where $type_1==0 and $type_2==0 (important !)
>
>  you were _not_ affected by the bug.
>
>  As soon as you had additional short range non bonded interactions  
> ($type_1 > 0 || $type_2 > 0)
>          e.g. "inter 0 1 <whatever> ... "
>  you were affected by the bug (or at least it was purely random, if  
> you were affected or not,
>  because the variable IA_parameters->LJ_min was not copied in  
> copy_ia_params and thus was uninitialized).
>
>  Bonded interactions e.g. "inter 0 fene ..." or long range  
> interactions e.g. "inter coulomb ..."
>  or weather you ran ESPResSo in parallel or on one CPU only had no  
> influence on the bug at all.
>
> * and again: the bug was present _only_ in the "bleeding egde" CVS  
> versions 2.1.1u to 2.1.2d
>
> * because somebody asked: yes, the ESPResSo testsuite detected the  
> bug (testcase mass.tcl did fail)
>  but somehow it could escape our attention until yesterday.
>
>
> Greetings,
> Torsten.
>
> Torsten Stuehn wrote:
> > Dear all,
> >
> > due to a bug, which appeared only in the CVS versions 2.1.1u  
> > (2009-02-09)
> > up to 2.1.2d (2009-03-09) some of the lennard-jones pair-interactions
> > were not
> > calculated correctly. All simulations that involved lennard-jones
> > interactions
> > (which is most likely all simulations !) and were done with these
> > versions of
> > ESPResSo are most likely wrong.
> >
> > The bug is fixed in version 2.1.2e (2009-03-09)
> >
> > PLEASE double check your simulations,  if you were using the above
> > mentioned ESPResSo versions !!!
> >
> > Greetings,
> > Torsten.
>
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