Density-matrix formalism with three-body ground-state correlations

Abstract

A density-matrix formalism which includes the effects of three-body ground- state correlations is applied to the standard Lipkin model. The reason to consider the complicated three-body correlations is that the truncation scheme of reduced density matrices up to the two-body level does not give satisfactory results to the standard Lipkin model. It is shown that inclusion of the three-body correlations drastically improves the properties of the ground states and excited states. It is pointed out that lack of mean-field effects in the standard Lipkin model enhances the relative importance of the three-body ground-state correlations. Formal aspects of the density-matrix formalism such as a relation to the variational principle and the stability condition of the ground state are also discussed. It is pointed out that the three-body ground-state correlations are necessary to satisfy the stability condition.

References in corpus (5)

• Ab-initio computation of neutron-rich oxygen isotopes
• Spurious modes in extended RPA theories
• Self Consistent Random Phase Approximation and the restoration of symmetries within the three-level Lipkin model
• Extended RPA with ground-state correlations in a solvable model
• Extended RPA with ground-state correlations

Cited by in corpus (6)

• Progress in Many Body Theory with the Equation of Motion method. Time dependent Density Matrix meets Self-Consistent RPA. Applications to solvable Models
• Second random-phase approximation, Thouless' theorem and the stability condition reexamined and clarified
• Self-Consistent RPA from a Coupled Cluster Wave Function Perspective
• Truncation scheme of time-dependent density-matrix approach
• Combining phase-space and time-dependent reduced density matrix approach to describe the dynamics of interacting fermions
• Recent applications of the subtracted second RPA method