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Journal of Physical Chemistry, Vol.99, No.9, 2929-2940, 1995
Multilevel Redfield Treatment of Bridge-Mediated Long-Range Electron-Transfer - A Mechanism for Anomalous Distance Dependence
The density matrix formalism is used to consider long-range electron transfer through a delocalized bridge system that is dissipatively coupled to a thermal bath. Under conditions when the bridge is weakly populated, a distance-independent transfer mechanism arises that eventually dominates the exponentially distance-dependent nonadiabatic tunneling process typically observed. This model offers a possible explanation for the anomalously rapid long-range photoelectron transfer recently observed by Barton and Turro et al. for donor and acceptor species intercalated into a DNA double helix (Science 1993, 262, 1025). Predicted electron-transfer rates are obtained by numerically solving the Redfield equation for the density matrix of the full donor-bridge-acceptor system in the presence of stochastic fluctuations induced by the bath.
Keywords:MOLECULAR-ORBITAL CALCULATIONS;BIOLOGICAL MOLECULES;CONDENSED PHASES;PROTON-TRANSFER;RADICAL IONS;DNA;QUANTUM;SYSTEMS;RELAXATION;PATHWAY