RPMD and Energy Minimizer

[Ali Eltareb]

Hi,

Can you use the energy minimizer for a PIMD configuration in OpenMM. So I have a configuration where I saved the positions of all the replicas. I then want to perform an energy minimizer to see what the new positions and minimized energy will be. I can do this for a classical system (i.e. using a Langevin Integrator), but when I try this with the RPMD integrator nothing happens. The energy and positions don't change.

I have also tried this with a simple harmonic potential, with two particles (and two beads on each particle) and still nothing happens.

Ali

[Peter Eastman]

The energy minimizer adjusts the positions stored in the Context. But RPMDIntegrator stores a whole list of different positions, one for each bead. If you just want to minimize the classical system, you can do that and then copy the positions over to every bead with integrator.setPositions().

[Ali Eltareb]

The energy minimizer won't work for a PIMD system then and I don't want to minimize the classical system. Is there a way around this?

[Peter Eastman]

If you set the temperature to 0 and run a short simulation, it should converge to a local minimum of the quantum system.