Excitation spectrum and liquid-structure function of a charged bose gas

Abstract

The excitation spectrum of a charged Bose gas in the high-density limit is calculated to two orders in the expansion parameter r_s^3/4 by the method of correlated basis functions (CBF). To O(r_s^3/4), the result differs from that obtained variationally, but agrees with that obtained by Ma and Woo via diagrammatic perturbation theory. The choice of the basis functions is, however, not unique. By choosing an alternate set of CBF which employs the ground-state eigenfunction as a correlating factor, we find it possible to extract from the excitation spectrum an expression for the liquid-structure function, also to two orders in r_s^3/4, which represents a new result. This new facet of CBF helps to demonstrate the flexibility of the method and the ease with which it can be applied to calculating properties of many-particle systems, model as well as realistic.