Gmx mdrun with -reprod does not reproduce a trajectory

User discussions
1

GROMACS version: 2023.2
GROMACS modification: No

Dear community,

To a previous question of mine I have been advised to run my simulations gmx mdrun -reprod (see original thread here).
I have tried using the -reprod option making sure, that all available seeds were the same in 2 independent runs as well as the machine being the same in the cluster I’m using. Nevertheless, the trajectory is different. Am I doing something wrong? The documentation is rather minimal regarding the -reprod option.

Please advise.

2

You can not use GPUs or dynamic load balancing and need to run on the same CPUs with the same software stack and exactly the same number of ranks and with the same number of threads. Even then we cannot guarantee that the results are identical, but I would expect them to be.