PyOpenCAP Documentation

PyOpenCAP is the Python API for OpenCAP, an open-source software aimed at extending the functionality of quantum chemistry packages to describe resonances. PyOpenCAP uses the pybind11 library to expose C++ classes and methods, allowing calculations to be driven within a Python interpreter.

PyOpenCAP is currently capable of processing quantum chemistry data in order to perform ‘projected’ complex absorbing potential calculations on metastable electronic states. These calculations are able to extract resonance position and width at the cost of a single bound-state electronic structure calculation.

To get started, please see our Getting Started page.

If you have questions or need support, please open an issue on GitHub, or contact us directly at gayverjr@bu.edu.

PyOpenCAP is released under the MIT license.

Supported Packages

Supported Methods

  • EOM-CC

  • FCI

  • MS-CASPT2 (and extended variants)

  • TDDFT

  • ADC (through ADCC)

  • MR-CI family of methods

Supported Potentials

  • Box (analytical integrals are now available!)

  • Smooth Voronoi

  • Custom CAP functions

Please see the keywords section for more details.

Other features

  • Python based eigenvalue trajectory analysis tools

  • Custom numerical integration grids

In development

  • Feshbach projection approaches

  • Tools for dyanmics on complex potential energy surfaces

Acknowledgements

  • We would like to give special thanks to Prof. Thomas Sommerfeld for generously providing us with a C++ implementation of analytical box CAP integrals. Please checkout his repository on GitHub for many implementations of L^2 methods for resonances!

  • We would like to thank Prof. John Burkardt for his C++ implementation of the Incomplete Gamma function. Many of his wonderful open source codes can be found at his website.

  • We would like to thank the Molecular Sciences Software Institute for funding this project. Please visit the MolSSI website for their educational resources, fellowship opportunities, and software projects!

  • We would like to thank Mushir Thodika from Temple University for his help in developing the interface with Columbus.