Psi4NumPy: An Interactive Quantum Chemistry Programming Environment for Reference Implementations and Rapid Development

Psi4NumPy demonstrates the use of efficient
computational kernels from the open-source Psi4 program through
the popular NumPy library for linear algebra in
Python to facilitate the rapid development of clear, understandable
Python computer code for new quantum chemical methods, while maintaining
a relatively low execution time. Using these tools, reference implementations
have been created for a number of methods, including self-consistent
field (SCF), SCF response, many-body perturbation theory, coupled-cluster
theory, configuration interaction, and symmetry-adapted perturbation
theory. Furthermore, several reference codes have been integrated
into Jupyter notebooks, allowing background, underlying theory, and
formula information to be associated with the implementation. Psi4NumPy tools and associated reference implementations
can lower the barrier for future development of quantum chemistry
methods. These implementations also demonstrate the power of the hybrid
C++/Python programming approach employed by the Psi4 program.