[gmx-users] Replica Exchange MD using Gromacs

[Mark Abraham]

On 1/04/2011 6:03 PM, Ruchi Gupta wrote:
> Dear gmx-users,
>
> I am facing some problems while running replica exchange MD using Gromacs.
>
> Few seconds after the job submission it ends with the following error message:
>
> "
> Initializing Replica Exchange
>
> Repl  There are 6 replicas:
> Multi-checking the number of atoms ... OK
> Multi-checking the integrator ... OK
> Multi-checking init_step+nsteps ...
> init_step+nsteps is not equal for all subsystems
>    subsystem 0: 0
>
>    subsystem 1: 50000
>    subsystem 2: 0
>    subsystem 3: 50000
>    subsystem 4: 0
>    subsystem 5: 50000
>
> -------------------------------------------------------
> Program mdrun, VERSION 4.5.4
> Source code file: main.c, line: 249
>
>
> Fatal error:
> The 6 subsystems are not compatible
>
> For more information and tips for troubleshooting, please check the GROMACS
> website athttp://www.gromacs.org/Documentation/Errors
>
> -------------------------------------------------------
>
> "
>
> I am using a "single .gro file" and "6 different md.mdp" files (at 6 different temperatures) for generating "6 .tpr files", respectively. But the simulation doesn't work.
>
>
> I have compared the ".tpr files" using "gmxdump" and "gmxcheck" Gromacs commands and they seem fine with respect to nsteps and init_step information.

So, to be clear, gmxcheck says that for no pair of .tprs does init_step 
or nsteps differ...

What is your mdrun command line? Are you using checkpoint files?

Mark