Introducing the Random Phase Approximation Theory

Random Phase Approximation (RPA) is the theory most commonly used to describe excitations of many-body systems. In this article, secular equations are obtained by using three different approaches: equation motion method, Green function perturbation and time-dependent Hartree–Fock theory. Each approach emphasizes specific aspects overlooked other methods. Extensions RPA treat continuum part excitation spectrum also pairing between particles composing system presented. Theoretical approaches which overcome intrinsic approximations outlined.