SOLID HELIUM,

Although the zero-point energy dominates the properties of the solid helium isotopes at low densities, more and more experimental evidence is accumulating to show that, except perhaps at a few singular points or limited regions of very low density, the thermodynamic properties of the solids are very similar to those of the other inert gas solids and can probably be explained by quasiharmonic lattice theory. Nevertheless, because of the large zero-point energy, a fundamental theoretical treatment of solid helium is still lacking. Author