TiDES: A time-dependent electronic structure code for real-time electron and spin dynamics

In this work, we present the TiDES (Time-Dependent Electronic Structure) code, an open-source real-time electronic structure theory package. The software is written in Python and interfaces with the Python-based Simulations of Chemistry Framework (PySCF), an open-source quantum chemistry library. The philosophy of the TiDES software package is to provide an incredibly modular real-time software package to allow for easy development and implementation of new methodology. The package allows for explicit time propagation of chemical systems within the spin-restricted, unrestricted, and generalized frameworks of both real-time time-dependent Hartree-Fock and real-time time-dependent density functional theory. Additional features include the ab initio Ehrenfest dynamics method for the simulation of coupled electronic and nuclear motion and the incorporation of a complex absorbing potential that enables the simulation of ionization events. To illustrate both the value of real-time dynamics and the intuitive nature of TiDES, we simulate spectroscopic properties and non-equilibrium electron and spin dynamics in several example systems. We also show how general external potentials can be defined and easily applied during time propagation. Lastly, the features within PySCF, such as spin-orbit coupling, interface readily with the real-time calculations, providing a powerful tool for simulating electron and spin dynamics with the capacity for extensive customization.