CHARMM Development Project Forums User Discussion & Questions Setup, I/O, and Basic questions Can USERE subroutine run in parallel?

Hi All,
I'm adding a user supplied energy and force in my simulation through the USERE subroutine. It works in a serial compilation of CHARMM. I was wondering if it should also work in a parallel version? Or is USERE not setup to run in parallel?

I'm using CHARMM v35b5.
Thanks,
Ed

Of course. This is entirely up to you, as with all parallel programming. You have to do the partitioning of the work across the nodes. Coordinates and forces are communicated outside the energy calculation, so you should not have to worry about that. Caveat: With the current (c35) parallel implementation you can also assume that each node has access to all coordinates, but this will change in the next release which will also support spatial decomposition. There may be other data that you have to communicate using MPI.

Thank you Prof Nilsson for the info. I'm just applying a constant force onto a single atom (the AFM module is not sufficient for some of the things I want to do, which is why I coded it in usere). So it sounds like I won't need to modify my USERE code for it to work in parallel.

The PULL command does apply a constant force (or periodic in time) to one or more atoms. See cons.doc

This is big help, thank you.
Ed