PySpawn: Software for Nonadiabatic Quantum Molecular Dynamics

The ab initio multiple spawning (AIMS)
method enables nonadiabatic
quantum molecular dynamics simulations in an arbitrary number of dimensions,
with potential energy surfaces provided by electronic structure calculations
performed on-the-fly. However, the intricacy of the AIMS algorithm
complicates software development, deployment on modern shared computer
resources, and postsimulation data analysis. PySpawn is a nonadiabatic
molecular dynamics software package that addresses these issues. The
program is designed to be easily interfaced with electronic structure
software, and an interface to the TeraChem software package is described
here. PySpawn introduces a task-based reorganization of the AIMS algorithm,
allowing fine-grained restart capability and setting the stage for
efficient parallelization in a future release. PySpawn includes a
user-friendly and interactive Python analysis module that will enable
novice users to painlessly adopt AIMS. As a demonstration of PySpawn’s
simulation capability and analysis module, we report complete active
space self-consistent field-based AIMS simulations of the 1,2-dithienyl-1,2-dicyanoethene
molecule, a promising molecular photoswitch.