Modeling Spin-Dependent Nonadiabatic Dynamics with Electronic Degeneracy: A Phase-Space Surface-Hopping Method

TL;DR

This paper introduces a phase-space surface-hopping method that incorporates Berry curvature effects due to electronic spin degeneracy, enabling more accurate simulation of spin-dependent nonadiabatic nuclear dynamics such as intersystem crossing.

Contribution

The authors develop a novel PSSH approach with a pseudo-diabatic ansatz that captures Berry curvature effects, improving the simulation of spin-dependent dynamics over existing methods.

Findings

PSSH accurately reproduces quantum dynamics in a simple model

Method captures Berry curvature effects in spin-dependent processes

Enables simulation of photochemical and spin relaxation dynamics

Abstract

Nuclear Berry curvature effects emerge from electronic spin degeneracy and canlead to non-trivial spin-dependent (nonadiabatic) nuclear dynamics. However, such effects are completely neglected in all current mixed quantum-classical methods such as fewest switches surface-hopping. In this work, we present a phase-space surface-hopping (PSSH) approach to simulate singlet-triplet intersystem crossing dynamics. We show that with a simple pseudo-diabatic ansatz, a PSSH algorithm can capture the relevant Berry curvature effects and make predictions in agreement with exact quantum dynamics for a simple singlet-triplet model Hamiltonian. Thus, this approach represents an important step towards simulating photochemical and spin processes concomitantly, as relevant to intersystem crossing and spin-lattice relaxation dynamics.