Tunneling Times in an Asymmetric Harmonic Double-Well with Application to Electron Transfers in Biological Macromolecules

Tunneling times were calculated in electron transfer processes using an asymmetric harmonic double-well model. The simplicity of a direct variational calculation in the approximate solution of the Schrödinger equation, along with the interpretation of tunneling times within the probabilistic framework of a two-level system, allows for the efficient and accurate determination of tunneling times with minimal computational cost. These calculations were applied to electron transfer processes in the study of the photosynthetic reaction center and in the context of catalysis in UV-induced DNA lesion repair and are in agreement with the experimental, computational, and theoretical results with which they were compared. It was seen that the donor–acceptor distance needed to be adjusted for closer agreement between the calculated and experimentally observed times. However, the adjusted values for this distance remain close to those reported in the literature.