What is WESTPA?

WESTPA (The Weighted Ensemble Simulation Toolkit with Parallelization and Analysis) is a high-performance Python framework for carrying out extended-timescale simulations of rare events with rigorous kinetics using the weighted ensemble algorithm of Huber and Kim (1996) (an overview is provided in this document and these slides). The software also includes (1) options for further enhancing the sampling efficiency through reassignment of weights according to either equilibrium or nonequilibrium steady state, and (2) plugins for using a weighted ensemble-based string method and the WExplore method.

Key features of the software:

  • Highly scalable. Nearly perfect scaling up to thousands of cores.
  • Interoperable. Designed to conveniently interface with any stochastic sampling engine (e.g., molecular dynamics, Brownian dynamics, and Monte Carlo engines).
  • Portable. The software can be used with any Unix operating system (e.g. Linux or OS X), including typical clusters and supercomputers.
  • Free and open source. All source code is available under the MIT open source license.

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Please cite us when using WESTPA:

MC Zwier, JL Adelman, JW Kaus, AJ Pratt, KF Wong, NB Rego, E Suárez, S Lettieri, DW Wang, M Grabe, DM Zuckerman, and LT Chong. “WESTPA: An interoperable, highly scalable software package for weighted ensemble simulation and analysis”. J. Chem. Theory Comput., 11: 800-809 (2015).

Obtaining and Installing WESTPA

Directions for the quick installation of WESTPA can be found here.

Documentation and Tutorials

Tutorials for using WESTPA can be found here. Our Wiki can be found here. Sphinx documentation can be found here. For additional support, you can search the archives of the WESTPA users mailing list.

We strongly suggest that you subscribe to the low-volume WESTPA user email list. Before posting issues to the list, please make sure you are using the most recent version of WESTPA and search the archives. We strive to be a good member of the scientific software community and suggest that you follow the checklist in these best practices.

Finally, while WESTPA is a powerful tool that enables expert simulators to access much longer timescales than is practical with standard simulations, there can be a steep learning curve to figuring out how to effectively run the simulations on your computing resource of choice. For serious users who have completed WESTPA tutorials and are ready for production simulations of their system, we invite you to contact Lillian Chong (ltchong AT pitt DOT edu) and Daniel Zuckerman (zuckermd AT ohsu DOT edu) about participating in their monthly Weighted Ensemble Data Club via video conferencing to help get your simulations off the ground.

To help us improve WESTPA please fill out a one-minute survey and consider contributing documentation or code to the WESTPA community.


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