Boson Correlation Energies from Reduced Hamiltonian Interpolation

The ground-state energies of interacting bosons are computed beyond the mean-field approximation by a new method which we call reduced Hamiltonian interpolation (RHI). In this interpolation the N-particle Hamiltonian is represented through a sequence of p-particle expanded and reduced Hamiltonians that give upper and lower bounds on the true energy. A synthesis of ideas from N-representability and dimensional interpolation, the RHI interpolates over the number p of quasiparticles (equivalent to spatial dimension) to calculate the N-particle energy as the mean of close upper and lower bounds. Application to bosons with harmonic interactions yields more than 99% of the correlation energy.