On the accuracy of surface hopping dynamics in condensed phase non-adiabatic problems

TL;DR

This paper benchmarks surface hopping methods against exact calculations for the spin-boson model, showing FSSH's surprising accuracy and the limited impact of decoherence corrections across various parameters.

Contribution

It provides a comprehensive comparison of surface hopping dynamics with exact results, highlighting the conditions under which FSSH performs well and assessing the effects of decoherence corrections.

Findings

FSSH is accurate over a wide parameter range.

Decoherence corrections improve accuracy but are not always significant.

Deviations from Marcus theory are small and bias-dependent.

Abstract

We perform extensive benchmark comparisons of surface hopping dynamics with numerically exact calculations for the spin-boson model over a wide range of energetic and coupling parameters as well as temperature. We find that deviations from golden-rule scaling in the Marcus regime are generally small and depend sensitively on the energetic bias between electronic states. Fewest switched surface hopping (FSSH) is found to be surprisingly accurate over a large swath of parameter space. The inclusion of decoherence corrections via the augmented FSSH (A-FSSH) algorithm improves the accuracy of dynamical behavior compared to exact simulations, but the effects are generally not dramatic, at least for the case of an environment modeled with the commonly used Debye spectral density.