First-passage time theory of activated rate chemical processes in electronic molecular junctions

Preston, Riley J., Gelin, Maxim F., and Kosov, Daniel S. (2021) First-passage time theory of activated rate chemical processes in electronic molecular junctions. Journal of Chemical Physics, 154. 114108.

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Abstract

Confined nanoscale spaces, electric fields, and tunneling currents make the molecular electronic junction an experimental device for the discovery of new out-of-equilibrium chemical reactions. Reaction-rate theory for current-activated chemical reactions is developed by combining the Keldysh nonequilibrium Green’s function treatment of electrons, Fokker–Planck description of the reaction coordinate, and Kramers first-passage time calculations. The nonequilibrium Green’s functions (NEGF) provide an adiabatic potential as well as a diffusion coefficient and temperature with local dependence on the reaction coordinate. Van Kampen’s Fokker–Planck equation, which describes a Brownian particle moving in an external potential in an inhomogeneous medium with a position-dependent friction and diffusion coefficient, is used to obtain an analytic expression for the first-passage time. The theory is applied to several transport scenarios: a molecular junction with a single reaction coordinate dependent molecular orbital and a model diatomic molecular junction. We demonstrate the natural emergence of Landauer’s blowtorch effect as a result of the interplay between the configuration dependent viscosity and diffusion coefficients. The resultant localized heating in conjunction with the bond-deformation due to current-induced forces is shown to be the determining factors when considering chemical reaction rates, each of which results from highly tunable parameters within the system.

Item ID: 67415
Item Type: Article (Research - C1)
ISSN: 1089-7690
Copyright Information: (C) AIP Publishing
Funders: Hangzhou Dianzi University
Date Deposited: 17 Mar 2021 04:18
FoR Codes: 51 PHYSICAL SCIENCES > 5102 Atomic, molecular and optical physics > 510201 Atomic and molecular physics @ 50%
51 PHYSICAL SCIENCES > 5108 Quantum physics > 510899 Quantum physics not elsewhere classified @ 50%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences @ 100%
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