Uncoupled oscillator model for interpreting second harmonic generation measurements of oriented chiral systems

Molecular modeling calculations of the electronically resonant nonlinear optical susceptibility of the archetypal chiral molecule binaphthol are shown to be qualitatively reproduced by considering two uncoupled naphthol molecules oriented in a manner similar to that in binaphthol. This remarkably simple uncoupled oscillator model reliably predicts the signs and relative magnitudes of the key elements within the molecular susceptibility tensor of binaphthol. These results suggest that surprisingly simple and intuitive physical models can often be constructed for qualitatively interpreting chiral-specific phenomena in nonlinear optical investigations of oriented chiral chromophores in thin films and at surfaces.