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WESTPA (The Weighted Ensemble Simulation Toolkit with Parallelization and Analysis) is an open-source software package that provides a high performance framework for carrying out extended-timescale simulations of rare events with rigorous kinetics using the weighted ensemble algorithm of Huber and Kim (1996). 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) a plugin for using a weighted ensemble-based string method.



  • WESTPA web site
  • Citation: 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).


Usage on Bridges


To see what versions of WESTPA are available type

module avail westpa

To see what other modules are needed, what commands are available and how to get additional help type

module help  westpa

To use WESTPA, include a command like this in your batch script or interactive session to load the WESTPA module:

module load westpa

Be sure you also load any other modules needed, as listed by the module help westpa command.