Semiempirical Helium Intermolecular Potential. II. Dilute Gas Properties

摘要

Parameter adjustments in a family of semiempirical potentials are reported. The result is a twohyphen;parameter potential incorporating theoretically determined dipolendash;dipole and dipolendash;quadrupole interactions which fits dilute helium gas data to within 6percnt; over the temperature range 1ndash;2000deg;K. The data fits near 50deg;K are not fully satisfactory, nor is the fit of viscosity data below 4deg;K. The sensitivity of the calculations to the inclusion of the dipolendash;dipole interaction for properties below 4deg;K is studied. The calculations using quantum mechanics show a greater sensitivity in the virial coefficient than the viscosity and differ from calculations using classical mechanics. The semiclassical limits of the calculations are discussed.