[gmx-users] odd replica excahnge

[leila salimi]

Dear Mark,

Thanks for your answer. I know what you meant about the error, but I tried
for 16 replicas and it runs! I don't know what it changed, because I use
the same cluster and the same version of gromacs.

Regards,
Leila

On Mon, Dec 1, 2014 at 6:18 PM, Mark Abraham <mark.j.abraham at gmail.com>
wrote:

> On Mon, Dec 1, 2014 at 4:39 PM, leila salimi <leilasalimi at gmail.com>
> wrote:
>
> > Dear gromacs users,
> >
> > I have tried different replica exchanges for my system, like 12, 14. I
> > found that with 15 replica, I can get 30-40 % ratio of exchanges between
> > replicas!
> >
>
> I don't understand. Below, you failed to run with 15 replicas.
>
>
> > When I sumbitted a simulation with 15 replicas, I did not get any result
> > and I got this error :
> >
> > ERROR: 0031-725  Failed to exec program mdrun_mpi_d; errno = 2
> > ERROR: 0031-619  execvp error: No such file or directory
> > ERROR: 0031-725  Failed to exec program mdrun_mpi_d; errno = 2
> > ERROR: 0031-619  execvp error: No such file or directory
> > ERROR: 0031-725  Failed to exec program mdrun_mpi_d; errno = 2
> > ERROR: 0031-619  execvp error: No such file or directory
> >
> > I don't have any idea about this error!! It might be beacuse of odd
> > replicas?!
>
>
> No, as you will see if you try to run with 16 replicas. You have not set up
> your environment so that mdrun is in the path / whatever.
>
>
> >   If yes, I don't know the point that why the number of replicas
> > should be even.
> >
>
> It doesn't have to be even. It's just usually efficient to do so because
> parallel computers sometimes require the use of resources in multiples of
> 2.
>
> Mark
>
>
> >
> > Kind Regards,
> > Leila
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