ORBITAL POLARIZABILITY MODEL FOR RAMAN OPTICAL ACTIVITY AND ELECTRIC FIELD PERTURBATIVE CALCULATIONS OF VIBRATIONAL OPTICAL ACTIVITY INTENSITIES

Abstract

Following the concepts of atomic and bond polarizabilities, an orbital polarizability model has been formulated for Raman optical activity (ROA) intensities. The operating equations are akin to those in atomic and bond polarizability models, and provide a convenient pathway to utilize molecular orbital schemes for predicting ROA intensities. This model for ROA is especially useful for adapting an extremely efficient electric field perturbative approach originally suggested by Komornicki and Melver in the context of evaluating Raman intensities. An interesting and useful feature of this model calculations is that vibrational circular dichroism, infrared absorption and Raman scattering intensities result automatically as by-products of an ROA calculation. An algorithum featuring all these advantages has been developed within CNDO MO scheme. The CPU time required for predicting ROA, VCD, Raman and IR intensities, for all 3N-6 vibrational modes, of all possible chiral deuterated cyclohexanones is found to be less than two hours.