AB-INITIO STUDIES OF THE POLARIZABILITIES OF RETINAL ANALOGS

Axial components of the polarizability, hyperpolarizability, and secon d order hyperpolarizability of retinal model molecules are calculated using the ab initio coupled-perturbed Hartree-Fock theory. Conformatio nal rearrangements are shown to affect some components in a systematic fashion. We also find that the general trend in the hyperpolarizabili ty behavior as a function of protonation and charge transfer is in agr eement with available experimental data. The second hyperpolarizabilit y 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 exper imental and theoretical developments towards the construction of molec ularly based nonlinear optical devices.