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Re: [ESPResSo] Addendum: Bug in Lennard-Jones interaction in ESPResSo ve
Re: [ESPResSo] Addendum: Bug in Lennard-Jones interaction in ESPResSo versions 2.1.1u up to 2.1.2d
Tue, 10 Mar 2009 23:34:29 -0400
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.
On Mar 10, 2009, at 12:15 PM, Torsten Stuehn wrote:
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
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.
Torsten Stuehn wrote:
due to a bug, which appeared only in the CVS versions 2.1.1u
up to 2.1.2d (2009-03-09) some of the lennard-jones pair-interactions
calculated correctly. All simulations that involved lennard-jones
(which is most likely all simulations !) and were done with these
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 !!!
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