New strategies for new organic molecules with large second order hyperpolarizabilities

Using data from computed observables of vibrational spectroscopy (frequency , infrared, Raman and hyper Raman intensities) we derive structural criteri a necessary to design new organic conjugated molecules with enhanced non li near optical responses. In this work, in particular, we focus on second ord er hyperpolarizability (gamma) and extract from our analysis the structural requirements necessary to reach large negative gamma values.