path-integral MD

Hi all, 2 new options were added this week to LAMMPS
for performing path-integral molecular dynamics (PIMD) simulations.

One by Yuxing Peng (U Chicago) called fix pimd, which
uses multiple replicas, one per bead in the PIMD polymer ring

model, so you launch a simulation using the multi-partition

command-line option for LAMMPS.

The other by Michele Ceriotti (EPFL) called fix ipi, which

uses LAMMPS as the MD engine, and wraps the code
with a Python wrapper called i-PI which implements the

PIMD algorithm. A LAMMPS-specific version of i-PI is
now included in tools/i-pi.

See the doc pages for details.

And thanks to Yuxing and Michele for the heavy lifting!

For those in the US, enjoy the Thanksgiving break,


And thanks also to Chris Knight (U Chicago) for working on
the new fix pimd.

I forgot to include him in the previous email.