Boson correlation energies from reduced Hamiltonian interpolation

The ground-state energies of interacting bosons are computed beyond the mea n-field approximation by a new method which we call reduced Hamiltonian int erpolation (RHI). In this interpolation the N-particle Hamiltonian is repre sented through a sequence of p-particle expanded and reduced Hamiltonians t hat give upper and lower bounds on the true energy. A synthesis of ideas fr om N-representability and dimensional interpolation, the RHI interpolates o ver the number p of quasiparticles (equivalent to spatial dimension) to cal culate the N-particle energy as the mean of close upper and lower bounds. A pplication to bosons with harmonic interactions yields more than 99% of the correlation energy.