A DYNAMICAL THEORY OF ELECTRON-TRANSFER - CROSSOVER FROM WEAK TO STRONG ELECTRONIC COUPLING

We present a real-time path integral theory for the rate of electron t ransfer reactions. Using graph theoretic techniques, the dynamics is e xpressed in a formally exact way as a set of integral equations. With a simple approximation for the self-energy, the rate can then be compu ted analytically to all orders in the electronic coupling matrix eleme nt. We present results for the crossover region between weak (nonadiab atic) and strong (adiabatic) electronic coupling and show that this th eory provides a rigorous justification for the salient features of the rate expected within conventional electron transfer theory. Nonethele ss, we find distinct characteristics of quantum behavior even in the s trongly adiabatic limit where classical rate theory is conventionally thought to be applicable. To our knowledge, this theory is the first s ystematic dynamical treatment of the full crossover region. (C) 1996 A merican Institute of Physics.