Together with the Zhu-Nakamura nonadiabatic transition formulas to treat the coupled electronic and nuclear quantum tunneling probability, we generalize quantum Kramers theory to electron-transfer rate constants. The application in the strongly condensed phase manifests that the approach correctly bridges the gap between the nonadiabatic (Fermi golden rule) and adiabatic (Kramers theory) limits in a unified way, and leads to good agreement with the quantum path integral data at low temperature.

• Received 21 July 2006

DOI:https://doi.org/10.1103/PhysRevA.74.032706