State Space Path Integrals for Electronically Nonadiabatic Reaction Rates

TL;DR

This paper introduces a state-space path integral approach combining quantum and classical methods to accurately compute electron transfer rates, including nonadiabatic and inverted regime effects, with good agreement to established theories.

Contribution

It develops a novel path integral method in state space for calculating electron transfer rates, incorporating dynamic recrossing corrections and multiple reaction coordinates.

Findings

Accurately predicts nonadiabatic ET rates in the normal Marcus regime.

Captures rate turnover in the Marcus inverted regime.

Achieves good agreement with Fermi's golden rule.

Abstract

We present a state-space-based path integral method to calculate the rate of electron transfer (ET) in multi-state, multi-electron condensed-phase processes. We employ an exact path integral in discrete electronic states and continuous Cartesian nuclear variables to obtain a transition state theory (TST) estimate to the rate. A dynamic recrossing correction to the TST rate is then obtained from real-time dynamics simulations using mean field ring polymer molecular dynamics. We employ two different reaction coordinates in our simulations and show that, despite the use of mean field dynamics, the use of an accurate dividing surface to compute TST rates allows us to achieve remarkable agreement with Fermi's golden rule rates for nonadiabatic ET in the normal regime of Marcus theory. Further, we show that using a reaction coordinate based on electronic state populations allows us to capture the turnover in rates for ET in the Marcus inverted regime.