Moments of the quadrupole oscillator strength distribution for O2, N2, CO, HF, HCl, N2O, CO2, OCS, CS2 and C2H2: ab initio sum rule calculations

Anisotropic moments, S2,m(k), of quadrupole oscillator strength distributions (QOSDs) are calculated for O2, N2, CO, HF, HCl, N2O, CO2, OCS, CS2 and C2H2. Sum rule methods are used with ground state multi-reference configuration interaction wave functions. These methods are found to be superior to propagator and pseudo-spectral methods used with finite basis sets for those moments that place emphasis on the high energy region of the spectrum. The QOSD moments, except S2,m(− 1), do not seem to be overly sensitive to either basis set or electron correlation effects.