Electronic Couplings and Energy Transfer Dynamics in the Oxidized Primary Electron Donor of the Bacterial Reaction Center

Abstract

of the energy transfer rates to P + . We present a qualitative description of the electronic energy transfer (EET) dynamics that involves mixing of the strongly allowed transitions in P + with a manifold of exotic lowerenergy transitions to facilitate EET on the observed time scale of 150 fs. This description is obtained using a three-step procedure. First, multireference configuration-interaction (MRCI) calculations are performed using the semiempirical INDO/S Hamiltonian to depict the excited states of P + . However, these calculations are qualitatively indicative but of insufficient quantitative accuracy to allow for a fully a priori simulation of the EET and so, second, the INDO results are used to establish a variety of scenarios, empirical parameters that are then fitted to describe a range of observed absorption and circular dichroism data. Third, EET according