Equilibrium charge distribution in organic donor-acceptor complexes: the role of coupling to intramolecular vibrations

The donor-acceptor molecular dimer is used for modeling the neutral-ionic transition. Charge transfer interaction and electron coupling to intramolecular vibrations are taken into account explicitly. A way of calculating the adiabatic potential as a function of charge transfer between donor and acceptor molecules is proposed. The relative significance of transfer integral and small-polaron binding energies of donor and acceptor molecules is discussed with respect to the feasibility of a nano-scale neutral-ionic transition.