This is module is undergoing heavy development. None of the API calls are final. This software is provided without any guarantees of correctness, you will likely encounter bugs.

If you are interested in this code, please wait for the official release to use it. In the mean time, to stay informed of development progress you are encouraged to:


A batteries-included toolkit for the GPU-accelerated OpenMM molecular simulation engine.

openmmtools is a Python library layer that sits on top of OpenMM to provide access to a variety of useful tools for building full-featured molecular simulation packages.

Features include:

  • high-quality Langevin integrators, including g-BAOAB, VVVR, and other splittings
  • integrators that support nonequilibrium switching for free energy calculations or nonequilibrium candidate Monte Carlo (NCMC)
  • an extensible Markov chain Monte Carlo framework for mixing Monte Carlo and molecular dynamics-based methods
  • enhanced sampling methods, including replica-exchange (REMD) and self-adjusted mixture sampling (SAMS)
  • factories for generating alchemically-modified systems for absolute and relative free energy calculations
  • a suite of test systems for benchmarking, validation, and debugging

Indices and tables