Crossover from nonadiabatic to adiabatic electron transfer reactions: Multilevel blocking Monte Carlo simulations

TL;DR

This paper uses advanced Monte Carlo simulations to explore the transition between nonadiabatic and adiabatic electron transfer regimes, providing exact data on transfer rates and dynamics across different conditions.

Contribution

It introduces a numerically exact simulation approach for the crossover region, overcoming the dynamical sign problem with a multilevel blocking algorithm.

Findings

Identifies the crossover regime in both classical and quantum limits.

Reveals complex electron transfer behaviors like multi-exponential decay.

Shows breakdown of rate descriptions due to vibrational coherence.

Abstract

The crossover from nonadiabatic to adiabatic electron transfer has been theoretically studied under a spin-boson model (dissipative two-state system) description. We present numerically exact data for the thermal transfer rate and the time-dependent occupation probabilities in largely unexplored regions of parameter space, using real-time path-integral Monte Carlo simulations. The dynamical sign problem is relieved by employing a variant of the recently proposed multilevel blocking algorithm. We identify the crossover regime between nonadiabatic and adiabatic electron transfer, both in the classical (high-temperature) and the quantum (low-temperature) limit. The electron transfer dynamics displays rich behaviors, including multi-exponential decay and the breakdown of a rate description due to vibrational coherence.