[gmx-developers] parallelization and accuracy

[Frauke Meyer]

Dear all, dear Justin,

I tried to change the pull code of the 3.1.4 version to enable it to
run in parallel. In principle it works, but the force I obtain starts to
differ (by 10^-3 kJ/mol/nm) from a sequential run from the 5th integration
step on. The force profiles of the seq. and parallel run finally diverge
after several 100 steps.
Any hint, what the reason might be for that? The only things I changed are
to add the stuff for parallel runs to the list of variables the procedures
of the pull code are called with (start, homenr, cr) and to restrict I/O
to the master node (actually I just transferred all changes for parallel
pulling of the cvs version into my code).

Thanks for all hints, which my mistakes might be.
Cheers,
Frauke