Many-body clusters in boson systems

Estimates of the four- and five-body elementary diagrams are used as input to the hypernetted chain equation for simple boson systems. Convergence of the variational method is judged by two criteria: the size of corrections to the energy and the agreement between two expressions for the energy which would be identical for an exact variational calculation. For these models, convergence is excellent below saturation, good in the region of saturation, and suspect at higher densities. Similar estimates could easily be made for Fermi systems with central correlations. (Auth.)