Dielectric properties of helium: Quantum statistical mechanics

Expressions for the second dielectric and Kerr virial coefficients and the first two moments of the associated spectral functions valid in quantum statistical mechanics are derived. Upper and lower bounds are derived for the second Kerr virial coefficient to enable an indirect evaluation when quantal effects are appreciable. Calculations of helium dielectric properties near 4 K are reported. The calculations incorporate approximations for the pair distribution function of gaseous helium and coupled Hartree-Fock results for the diatom polarizability. Structure factors calculated from the distribution functions and the calculated anisotropy moments are in good agreement with experiment. The calculated second dielectric virial coefficient at 4 K is in order-of-magnitude agreement with experiment and reflects an imprecise knowledge of the incremental mean polarizability of the helium diatom.