PyRETIS is a Python library for rare event molecular simulations with emphasis on methods based on transition interface sampling and replica exchange transition interface sampling. The papers describing the PyRETIS program can be found here: https://doi.org/10.1002/jcc.24900 (PyRETIS 1, 2017) and here: https://doi.org/10.1002/jcc.26112 (PyRETIS 2, 2019).

The work on PyRETIS was initiated by Titus van Erp and is used in the research and teaching activities in the theoretical chemistry group at the Norwegian University of Science and Technology.

PyRETIS is open source and is released under a GNU Lesser General Public license v2.1+. If you are interested in contributing to the PyRETIS project, please have a look at the developer guide and visit our git repository https://gitlab.com/pyretis/pyretis.

The current PyRETIS version is 2.5.0. For an overview of the official PyRETIS releases, please visit our git repository: https://gitlab.com/pyretis/pyretis/-/releases.

Since version 2.4, PyRETIS includes PyVisA, a program created to facilitate post-processing and data analysis.

The PyRETIS team

Head authors & project leaders:

Core Developers:


Former Developers:


  • Oda Dahlen
  • Christopher Daub
  • An Ghysels
  • Mahmoud Moqadam
  • César A. Urbina-Blanco
  • Jocelyne Vreede
  • Magnus Heskestad Waage

To cite us:

When using PyRETIS, or one of our libraries, please cite us!

Software papers:

Theory papers from our group: