Nonperturbative method of electron transfer via a midway molecule

In the theory of Sumi and Kakitani on electron transfer (ET) via a midway molecule, the overall ET was formulated using the second-order perturbation method and phenomenologically incorporating the renormalization factor in the intermediate state to escape from the divergence of the rate. In this Letter, we developed a nonperturbative theory of the ET via a midway molecule and we have succeeded in naturally deriving the above renormalization factor under certain approximations.