Vibronic energy localization in weakly coupled small molecular aggregates

Within a one-exciton picture, molecular dimers (M1–M2) possess excited states of even and odd parity which correspond to linear combinations of locally excited configurations ( M 1 ∗ – M 2 , M 1 – M 2 ∗ ). If this symmetry is broken, the excitation energy localizes in one or the other monomer. We perform time-dependent quantum calculations on dimer and trimer aggregates which are subject to time-dependent perturbations. The latter induce exciton localizations which are influenced by the monomer vibrational degrees-of-freedom. This influence is characterized by comparison with purely electronic models.