Higher Multipole Polarizabilities Research Articles

Dynamic multipole polarizabilities, reduced spectra, and interaction coefficients for N2 and CO

Reliable ab initio reduced spectra that serve to calculate dynamic polarizabilities as well as long-range interaction coefficients are presented. The reduced spectra are constructed from perturbed functions that are computed in the single excitation multi-reference averaged coupled pair approach. The static dipole polarizabilities are of the same quality as values obtained in a recent study using elaborated coupled cluster expansions. The dynamic dipole polarizabilities are in excellent agreement with all experimental data available. The higher multipole polarizabilities (l⩽3) are also expected to be the most reliable ones up to date. The interaction coefficients for the N2–N2 interaction perfectly match the coefficients obtained from semiempirical anisotropic oscillator strength distributions. For the CO–CO interaction, however, the same quantities differ by up to 10%. We believe our coefficients to be accurate to 3%.

Molecular theory of optical polarization and light scattering in dielectric fluids. II. Extensions and applications

A microscopic theory of light scattering developed in a previous publication, which incorporates all intermolecular-force effects, is here extended and applied to specific experimental situations. The consistency between the molecular theory and macroscopic theories of light scattering is established. The formal theory is then elaborated to include explicitly the contributions of higher-multipole hyperpolarizabilities, and of nonlinear effects of the external field. The many-body hyperpolarizabilities are expanded in terms of the corresponding single-particle operators and intermolecular forces. Three specific applications of this formalism are considered: (a) collision-induced forbidden Raman scattering in which higher-multipole polarizabilities are shown to partake; (b) collision-induced second-harmonic generation (SHG) by fluids of centrosymmetric molecules; and (c) SHG by atomic fluids. The latter process is shown to contain direct information on the three-particle correlation function.