Python‐based simulations of chemistry framework (PySCF) is a
general‐purpose electronic structure platform designed from the ground
up to emphasize code simplicity, so as to facilitate new method
development and enable flexible computational workflows. The package
provides a wide range of tools to support simulations of finite‐size
systems, extended systems with periodic boundary conditions,
low‐dimensional periodic systems, and custom Hamiltonians, using
mean‐field and post‐mean‐field methods with standard Gaussian basis
functions. To ensure ease of extensibility, PySCF uses the Python
language to implement almost all of its features, while
computationally critical paths are implemented with heavily optimized
C routines. Using this combined Python/C implementation, the package
is as efficient as the best existing C or Fortran‐based quantum
chemistry programs.