Virial Coefficients and Intermolecular Potential of Helium

Abstract

The intermolecular potential of helium has been determined from an analysis of the second and the third virial coefficients above the Boyle temperature, where the virial coefficients can be expanded into power series on h², the square of Planck’s constant. The series have been calculated up to the term proportional to the third power of h² in case of the second virial coefficient and up to the term proportional to the first power of h² in case of the third virial coefficient. The following conclusion has been drawn. The two-body system of He⁴ atoms has a discrete energy level while the two-body system of He³ atoms has no discrete level.