Dynamics of strongly correlated quantum systems from an extended Singwi‐Tosi‐Land‐Sjölander closure for the BBGKY hierarchy

Abstract

The BBGKY hierarchy in the Wigner representation is used with an extended Singwi‐Tosi‐Land‐Sjölander (STLS) ansatz for the two‐particle distribution function [H. Kählert, G. J. Kalman, and M. Bonitz, Phys. Rev. E 90, 011101 (2014)] to study the density response function and the dispersion relation of collective modes in a strongly coupled quantum system. It is shown that the local field correction (LFC) and the dispersion relation reduce to the results of the Quasi‐Localized Charge Approximation (QLCA) in the classical limit. In the quantum case, the LFC acquires a frequency‐dependence, similar to the quantum version of the STLS theory. The dispersion relation is governed by a generalization of the QLCA dynamical matrix. The results are expected to be relevant for the analysis of collective modes in quantum liquids with strong correlations.