Different Flavors of Exact-Factorization-Based Mixed Quantum-Classical Methods for Multistate Dynamics

TL;DR

This paper compares various exact-factorization-based mixed quantum-classical methods for simulating multistate electron-ion dynamics, focusing on their performance, approximations, and adherence to physical conditions in complex systems.

Contribution

It provides a systematic comparison of different exact-factorization approaches for multistate dynamics, highlighting their advantages and limitations in complex molecular and polaritonic systems.

Findings

Coupled trajectories improve accuracy over auxiliary trajectories.

Approximate methods can violate zero population transfer conditions.

Energy conservation varies among different approaches.

Abstract

The exact factorization approach has led to the development of new mixed quantum-classical methods for simulating coupled electron-ion dynamics. We compare their performance for dynamics when more than two electronic states are occupied at a given time, and analyze: (1) the use of coupled versus auxiliary trajectories in evaluating the electron-nuclear correlation terms, (2) the approximation of using these terms within surface-hopping and Ehrenfest frameworks, and (3) the relevance of the exact conditions of zero population transfer away from nonadiabatic coupling regions and total energy conservation. Dynamics through the three-state conical intersection in the uracil radical cation as well as polaritonic models in one dimension are studied.