Effective quantum reorganization energy for electron transfer
Abstract
The Marcus theory expression for the rate of non-adiabatic electron transfer is widely used across a range of physical conditions. Although Marcus theory defines the reorganization energy classically, here we show that the reorganization parameter governing the activation barrier for normal-region electron transfer is most generally a quantum mechanical object that depends on the electronic coupling, coinciding with the Marcus picture only in the limit of vanishing electronic coupling. This result unifies the physical description of electron-transfer activation barriers across the adiabatic and non-adiabatic regimes and formally predicts that Marcus-like rate expressions remain accurate beyond their traditional non-adiabatic domain of validity. These insights allow us to derive a closed-form expression for the curvature of the current-overpotential relation for electron-transfer-limited reactions at the electrochemical interface, now formally applicable to both inner-sphere and outer-sphere processes.
Cite
@article{arxiv.2510.10996,
title = {Effective quantum reorganization energy for electron transfer},
author = {Ethan Abraham and Junghyun Yoon and Troy Van Voorhis and Martin Z. Bazant},
journal= {arXiv preprint arXiv:2510.10996},
year = {2026}
}