Effect of Attractive Forces on the Solid-Superfluid Transition inHe4at Absolute Zero

The effect of attractive interactions between helium atoms on the solid-superfluid transition in ${\mathrm{He}}^4$ at absolute zero is considered. It is found that the density of the solid-superfluid transition does not depend on the strength of the attractive interactions, but only on the mass of the particles and the strength of the repulsive interactions. The density at which the system reaches zero pressure increases with increasing strength of attractive forces, so that sufficiently large attractive forces can inhibit the transition. Quantitative estimates and comparisons are made of the zero-pressure density and of the transition density, for different masses and for different strengths of attractive interactions.