SECOND HYPERPOLARIZABILITIES OF MOLECULAR AGGREGATES: INTERMOLECULAR ORBITAL-INTERACTION AND SPIN-CONFIGURATION EFFECTS

摘要

Toward an understanding of intermolecular-interaction effects on the third-order nonlinear optical properties of nanostructured molecular aggregates, we investigate the longitudinal second hyperpolarizabilities (γ) of model dimers composed of neutral (C_5H_7) and charged (C_5H_7~+) monomers using ab initio molecular orbital methods. It is found that π-π orbital interaction in the stacking direction remarkably affects the γ values of dimers, while the difference in spin configuration hardly causes significant changes in γ for the present models due to weak exchange interactions between monomers.