A high-pressure calculation used to determine the helium pair interaction

The pressures and compressibilities of solid³He and⁴He are calculated over the volume range 3 cm³/mole V 13 cm³/mole, using a simple Heitler-London variational approach. For volumesV 8 cm³/mole, the calculation is sufficiently exact to make possible a meaningful comparison of the results, obtained using four different semiphenomenological forms for the potential, with experimental data. The results indicate that the Beck potential is the best existing representation of the helium pair potential.