VIBRATIONAL EFFECTS FOR THE DISPERSION-ENERGY AND DISPERSION-POLARIZABILITY COEFFICIENTS FOR INTERACTIONS BETWEEN H, HE, AND H2

The effects of zero-point and ''pure'' vibration on the dispersion-energy and the dispersion-polarizability coefficients for interactions between H and H-2, He and H-2, and H-2 and H-2, are investigated. It is found that calculations of these coefficients which use the vibrationally averaged internuclear separation for H-2, differ from the properly vibrationally averaged values by the order of one percent. So-called pure vibrational contributions are found to be negligible.