Connection between simple models and quantum chemical models for electron-transfer tunneling matrix element calculations: A Dyson's equations-based approach

Pathwaylike models for electron transfer (ET) are based on simple Hamiltonians that are tuned to provide the proper wave function distance decay and sign alternation of the wave function with every bond. This alternation plays a vital role on interference effects among different tubes. To verify the validity of these models and to obtain ''quantitative effective'' parameters (at extended Huckel level) to use in pathwaylike Hamiltonians, a series of calculations (exact and approximate) has been performed for several ideal chainlike bridges. Particular emphasis is given to the dependence on the tunneling energy, length of interaction among orbitals, side groups, boundary effects, and nonorthogonality of the orbital basis. We also show how the ET rate along a single physical pathway is determined by competition among several ET decay modes.