STOCHASTIC-THEORY OF ADIABATIC ELECTRON-TRANSFER REACTIONS IN POLAR MEDIA

A dynamic theory of adiabatic electron transfer (ET) reactions is formulated in the framework of the Born-Kirkwood-Onsager model (the continuum medium with a cavity). The dynamical operator governing the time evolution of the inertial polarization field is derived using the linear response approach in terms of the complex dielectric permittivity function. The free energy functional is constructed which serves as a potential energy surface for an ET process. A systematic method of introducing collective medium modes works for special types of interaction between the medium and the ET chemical subsystem. The corresponding equation of motion reduces to a generalized Langevin equation (GLE). The rate constant expression can be extracted from this GLE either under the Grote-Hynes approximation or in the framework of the Sumi-Marcus asymptotic treatment. The way of a further development of the theory is discussed.