AB-INITIO STUDIES OF THE POLARIZABILITIES OF RETINAL ANALOGS

Axial components of the polarizability, hyperpolarizability, and second order hyperpolarizability of retinal model molecules are calculated using the ab initio coupled-perturbed Hartree-Fock theory. Conformational rearrangements are shown to affect some components in a systematic fashion. We also find that the general trend in the hyperpolarizability behavior as a function of protonation and charge transfer is in agreement with available experimental data. The second hyperpolarizability of the protonated Schiff base is found to be highly dependent on the adopted geometry optimization. We explore a possible explanation for this as well as present a brief discussion with regard to future experimental and theoretical developments towards the construction of molecularly based nonlinear optical devices.