Theoretical search for molecular aggregates with strong non-linear opticalactivity

Electronic correlation and electron-molecular vibration (EMV) coupling are effects of the same order of magnitude in molecular donor-acceptor complexe s. A model is considered where both effects are taken into account explicit ly. Calculations of static first and second hyperpolarizabilities are repor ted for a planar aggregate of five sites with two electrons which models mo lecules with two pairs of different side groups attached to the central par t. These results may be used for future synthesis of molecules with require d optical properties. (C) 2001 Elsevier Science B.V. All rights reserved.