Correlated dipole oscillator sum rules

Abstract

The second order polarization propagator approximation (SOPPA) has been applied to the calculation of the dynamic dipole polarizability, α(ω), of the molecules N2, C2H2, CO, and HCN. The dipole oscillator sum rules S(-4) and S(-6), which are the leading contributions to the Cauchy expansion of the polarizability, have also been evaluated at SOPPA level, using a polynomial fit to this expansion. These are the first reported values of the higher sum rules obtained using the SOPPA approach, and we observe excellent agreement with experiment. We also discuss the applicability of scaling or additivity expressions for obtaining the correlated polarizability from static correlated and dynamic uncorrelated quantities. © 1994 American Institute of Physics.