Adiabatic Rate Processes at Electrodes. I. Energy-Charge Relationships

Abstract

The distinction between adiabatic and nonadiabatic reaction mechanisms at an electrode/solution interface is emphasized; in general, only adiabatic or near-adiabatic paths are important in thermally activated reactions. The role of the dielectric in determining the course of such reactions is discussed. A general interpretation of the transfer coefficient and an account of the activation process in simple systems are given in terms of the distribution of electron charge density in the transition state; these are shown to be in good accord with experiment. The conventional approach to these problems, in which an approximate potential-energy path for the reaction is calculated from intersecting potential-energy curves for the initial and final states of the system, is criticized, and an alternative representation in terms of charge variation is proposed.

BODIPY derivatives as n-type organic semiconductors: Isomer effect on carrier mobility

“…Our simulation model is based on first-principle quantum mechanics (QM) calculations combined with Marcus-Hush theory [59,60]. For the calculations of the intermolecular effective electronic coupling, we calculate the spatial overlap (S ij ), charge transfer integrals (J ij ), and site energies (e i , e j ):…”

Computationally connecting organic photovoltaic performance to atomistic arrangements and bulk morphology

“…If the initial and destination sites are spatially proximal, then there is increased overlap between the frontier molecular orbitals and it becomes easier for charge carriers to hop between them, giving a faster rate, k i→j . Generally, transfer integrals are approximated by using the energy splitting in dimer method [74,103,104], based on the framework of the Marcus-Hush two-state model [105,106]. For the charge transport of holes, this operates on the assumption that, as a pair of chromophores are brought closer together from isolation, the HOMO level of the dimer splits, producing new HOMO and HOMO-1 energy levels.…”

Simple formula for asymmetric Marcus–Hush kinetics

“…The microscopic electron transfer theory [13], pioneered by Marcus [19,20] and Hush [11,12], has achieved great success in predicting reaction rates for both homogeneous bulk reactions and heterogeneous electrode reactions [21] that exhibit curved Tafel plots, which cannot be described by the phenomenological Butler-Volmer (BV) equation [2]. The fundamental assumption of Marcus-Hush (MH) theory is a quadratic dependence of the (excess) free energy of the reactant and product along a configurational reaction coordinate mainly associated with solvent reorganization, where electron transfer occurs iso-energetically at a transition state defined by the intersection of these parabolae.…”