As of November 2024 I'm no longer in academia. I've no longer access to commerical/closed-source codes like Gaussian or Turbomole, nor to paywalled scientific papers. Consider pysisyphus to be unmaintained.

Use at your own risk.

pysisyphus is a software-suite for the exploration of potential energy surfaces in ground- and excited states. It implements several methods to search for stationary points (minima and first order saddle points) and the calculation of minimum energy paths by means of IRC and Chain of States methods like Nudged Elastic Band and Growing String.

Furthermore it provides tools to easily analyze & modify geometries (aligning, translating, interpolating, ...) and to visualize the calculation results.

Required energies, gradients and hessians are calculated by calling external quantum chemistry codes. Alternatively pysisyphus can also be used as a library to implement custom quantum chemistry workflows.

Further information can be found in the Open Access pysisyphus paper.

Please have a look at the documentation.

Fully internal coordinate transition state search for the famous alanine dipeptide isomerization reaction, using the xtb calculator and the growing string method.

If any problems arise, please open an issue and I'll see if I can help if my time permits it. Contributions are welcome, so feel free to submit a PR.