A molecular theory of the nonadiabatic electron transfer rate

4 A molecular theory of the nonadiabatic electron transfer rate 

Equation (16.51) was derived from the Landau-Zener theory for transitions between electronic states at the crossing of the corresponding potential surfaces, however 

In addition, in the absence of coupling between the electronic and vibrational motions it becomes 

It is important to realize that the only approximations that enter into this rate expression is the use of the Fenni golden-rule, which is compatible with the weak coupling nonadiabatic limit, and the Condon approximation which is known to be successful in applications to electronic spectroscopy. The solvent effect on the electronic process, including the slow dielectric response, must arise from the FC factor that contains contributions from all the surrounding intermolecular and intramolecular nuclear degrees of freedom. In fact, if the nuclear component of the solvent polarization was the only important nuclear motion in the system, then on the classical level of treatment used by Marcus Eqs (16.53) and (16.51) with Ea given by (16.49) should be equivalent. This implies that in this case 

We have thus found that the reorganization of the nuclear environment that accompanies electron transfer involves the change in the molecular configuration, that is, shifts in the equilibrium positions of the nuclei between the two electronic 

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A MOLECULAR THEORY OF THE NONADIABATIC ELECTRON TRANSFER RATE... 

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