Classical Approach to Multichromophoric Resonance Energy Transfer

A classical formulation of the quantum multichromophoric theory of resonance energy transfer is developed on the basis of classical electrodynamics. The theory allows for the identification of a variety of processes of different order-in-the-interactions that contribute to the energy transfer in molecular aggregates with intra-coupling in donors and acceptor chromophores. Enhanced rates in multichromophoric resonance energy transfer are shown to be well described by this theory. Specifically, in a coupling configuration between N_{\mathrm{A}}$ acceptors and $N_{\mathrm{D}}$ donors, the theory correctly predicts an enhancement of the energy transfer rate dependent on the total number of donor-acceptor pairs. As an example, the theory, applied to the transfer rate in LH~II, gives results in excellent agreement with experiment. Finally, it is explicitly shown that as long as linear response theory holds, the classical multichromophoric theory formally coincides with the quantum formulation.