[gmx-users] Different average H bonds with different g_hbond releases

[Luigi CAVALLO]

Hi, 

we have a .xtc and .tpr file. We were interested in the
average number of H-bonds in the last 10ns of a 60ns long trajectory. We
analyzed the jobs as g_hbond -f traj1_0-60ns.xtc -s topol.tpr -b 50000
-num hbond.xvg. We are displaced by having a different number depending
on the g_hbond release. 

Release 4.5.4 : Average number of hbonds per
timeframe 163.620 out of 118112 possible 

Release 4.5.5 : Average
number of hbonds per timeframe 168.168 out of 118112 possible 

Looking
at the hbond.xvg file, the number of H-bonds in each frame are clearly
different between the two releases. How is this possible ? We checked
single versus double precision g_hbonds, same behavior. We checked that
the initial part of the output, i.e. all the various g_hbond defaults,
they are the same. We tested different computers and compilations, same
behavior. 

The topology and the md run were done with release 4.5.4 if
this could be a relevant information. 

Thanks, 

Luigi