Resonant coherence in photosynthetic electronic energy transfer by site-dependent pigment-protein interactions.

We have numerically examined the effect of site-dependent reorganization on the dynamics of coherent electronic excitation energy transfer in a donor and acceptor pair of photosynthetic pigment-protein complex. Using the quasi-adiabatic propagator path integral method (QUAPI), we have found that a specific proportionality between the site-energy mismatch ϵ and the site-reorganization energy mismatch λ simultaneously increases the length and robustness of the quantum coherence. This behavior is associated with a Rabi type resonance that is manifested in the amplitude and frequency in the coherent portion of the population dynamics. Impact of the resonance on robustness of the coherence under static disorder is also discussed.