Multi-particle–hole excitations in many-body Fermi systems

Abstract

We formulate a microscopic theory for calculating the dynamic structure function of 3 He and other strongly interacting Fermi liquids. The theory is a generalization of the correlated basis function theory for the dynamics of 4 He and includes time-dependent two-particle—two-hole excitations. It may also be interpreted as a systematic extension of the random-phase approximation (RPA). Comparison of numerical results with experiments show a significant improvement of the excitation spectrum over RPA predictions while maintaining the accuracy of prediction of ground-state quantities like the static structure function.