Intermolecular electronic coherences and local field effects in optical spectra of PPV-oligomer dimers Original Research Article

Optical spectra of an assembly of conjugated molecules are calculated using nonlocal molecular response functions which take into account electrostatic interactions with the surrounding molecules. The present approach provides a computationally efficient procedure for calculating the electrodynamics of interacting molecules with delocalized electronic states. Intramolecular and intermolecular electronic coherences are studied by examining the reduced single electron density matrix. Both electrostatic (multipolar) and chemical (exchange) interactions are incorporated in a unified formalism. Perturbative treatment of the latter allows a systematic extension of the local field approximation. Applications are made to dimers of PPV oligomers.