Ground-State Energy of SolidHe3

The ground-state energy of solid ${\mathrm{He}}^3$ is evaluated by means of a perturbation expansion. The unperturbed Hamiltonian chosen localizes each atom at a given site. As such, the formalism is one of distinguishable particles. No a priori self-consistency of the single-particle potential is assumed. Two-particle diagrams are summed to all orders by means of a set of Bethe-Goldstone equations.