Electronic coupling and resonance energy transfer between chromophores plays a crucial role in solar energy conversion in natural and artificial photosynthetic complexes, in measurements of protein folding, in hysteresis properties of molecular electronic devices, and in exciton-polariton propagation in crystals. We investigate electronic interactions in several prototypical bichromophore systems, such as benzene dimer, diphenylmethane (DPM), and chlorophyll dimers. Accurate description of the electronic structure of these bichromophores is challenging for theory. For instance, in flexible diphenylmethane, small splitting between the exciton states (123 cm-1 from experiment) and sensitivity of the transition dipole moment to the relative orientation of the rings leads to curious shapes and crossings of the potential energy surfaces of the exciton states. By the example of these prototypical systems, we investigate accuracy of the perturbative approach, in which the coupling strength is estimated by using transition densities of the individual chromophores, as compared to exact supermolecular calculations.

Electronic structure and exciton coupling in prototypical bichromophores

240th National Meeting (2010)

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