A microscopic study of the ground-state properties and excitation spectrum of an interacting Bose system using the combined method relating correlated-basis-functions and the canonical transformations

Previously, Wong and Fung proposed a microscopic theory which combines the methods of the Correlated-Basis-Functions and the canonical transformation approach in studying a many-boson system. Using a model potential function which satisfies certain criteria, a one-to-one mapping between real- and quasi-particle spaces exists. We have expressed the explicit forms of the relevant transformation matrix elements in terms of the two-particle correlation function. Using our special model for the two-particle potential function, we calculate the ground-state properties and the low-lying excitation spectrum of a Bose system with liquid helium density and report that numerical results agree reasonably well with experimental data.