Penguin: A Python-Based Program for Electronic Structure Calculations Based on Coupled Cluster Theory

The Penguin program is an open-source Python program
that enables
molecular property and spectroscopy calculations using coupled cluster
theory and perturbation theory approaches, such as cluster perturbation
theory and Mo̷ller-Plesset perturbation theory. This is the
first time that cluster perturbation theory approaches have been made
available in open source software. The program is written in a modular
and object-oriented fashion and features a matrix element library
for evaluating commonly encountered terms in coupled cluster theory.
The Penguin program supports interactive usage through Jupyter notebooks,
making it ideal for educational purposes as well as rapid prototyping
of novel coupled cluster and perturbation theory methods. In the current
version, the program also features an OpenMP/MPI parallel version
of the CC2 model highlighting the high performance computing potential
that can be realized using this strategy of software design.