Venkatramani Ravindra, Wierzbinski Emil, Waldeck David H, Beratan David N
Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India.
Faraday Discuss. 2014;174:57-78. doi: 10.1039/c4fd00106k. Epub 2014 Oct 3.
A theoretical framework is presented to describe and to understand the observed relationship between molecular conductances and charge transfer rates across molecular bridges as a function of length, structure, and charge transfer mechanism. The approach uses a reduced density matrix formulation with a phenomenological treatment of system-bath couplings to describe charge transfer kinetics and a Green's function based Landauer-Buttiker method to describe steady-state currents. Application of the framework is independent of the transport regime and includes bath-induced decoherence effects. This model shows that the relationship between molecular conductances and charge transfer rates follows a power-law. The nonlinear rate-conductance relationship is shown to arise from differences in the charge transport barrier heights and from differences in environmental decoherence rates for the two experiments. This model explains otherwise puzzling correlations between molecular conductances and electrochemical kinetics.
本文提出了一个理论框架，用于描述和理解分子电导与跨分子桥的电荷转移速率之间的观测关系，该关系是长度、结构和电荷转移机制的函数。该方法使用了一种约化密度矩阵公式，对系统-浴耦合进行唯象处理来描述电荷转移动力学，并使用基于格林函数的朗道尔-布蒂克尔方法来描述稳态电流。该框架的应用与传输机制无关，并包括浴致退相干效应。该模型表明，分子电导与电荷转移速率之间的关系遵循幂律。非线性的速率-电导关系被证明是由两个实验中电荷传输势垒高度的差异以及环境退相干速率的差异引起的。该模型解释了分子电导与电化学动力学之间原本令人困惑的相关性。
