The Chronus Quantum software package

TLDR

ChronusQ is an open‑source software infrastructure designed to solve challenging ab initio electronic structure problems. The paper examines the current state of the code base and discusses ongoing developments and developer contributions. ChronusQ implements consistent time‑dependent and spin‑dependent treatments, includes relativistic effects, supports uniform finite magnetic fields via gauge‑inclusion atomic orbitals, and runs in parallel using modern C++ with MPI and OpenMP.

Abstract

The Chronus Quantum (ChronusQ) software package is an open source (under the GNU General Public License v2) software infrastructure which targets the solution of challenging problems that arise in ab initio electronic structure theory. Special emphasis is placed on the consistent treatment of time dependence and spin in the electronic wave function, as well as the inclusion of relativistic effects in said treatments. In addition, ChronusQ provides support for the inclusion of uniform finite magnetic fields as external perturbations through the use of gauge-including atomic orbitals (GIAO). ChronusQ is a parallel electronic structure code written in modern C++ which utilizes both message passing (MPI) and shared memory (OpenMP) parallelism. In addition to the examination of the current state of code base itself, a discussion regarding ongoing developments and developer contributions will also be provided.