A Resolution to the Marcus-Rehm-Weller Paradox in Electron Transfer

Ethan Abraham

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arXiv · 2511.01909

A Resolution to the Marcus-Rehm-Weller Paradox in Electron Transfer

Ethan Abraham

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Abstract

Marcus theory famously predicts that electron-transfer rates decrease once the thermodynamic driving force exceeds the reorganization energy. Yet many systems instead exhibit Rehm-Weller kinetics characterized by rate saturation rather than decrease. Here we show that these apparently contradictory phenomenologies emerge as opposite physical limits of the same two-state quantum Hamiltonian. In the normal region, the model recovers both Marcus and Rehm-Weller behavior. In the inverted region, however, it predicts Marcus's decreasing rate in the nonadiabatic limit but Rehm-Weller saturation in the adiabatic limit. Using physically realistic reorganization energies and electronic coupling values, we show that Rehm-Weller's data can be quantitatively reproduced within a microscopic quantum model without invoking phenomenological corrections.

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Ethan Abraham. 2025-10-31. A Resolution to the Marcus-Rehm-Weller Paradox in Electron Transfer. https://arxiv.org/abs/2511.01909

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