Quasiparticle random-phase approximation with an optimal ground state

Abstract

A new Quasiparticle Random Phase Approximation approach is presented.The corresponding ground state is variationally determined and exhibits a The random phase approximation (RPA) and its quasiparticle (qp) generalization (QRPA) are powerful tools for describing the collective degrees of freedom of many-fermion systems in various branches of physics like nuclear physics, solid state, plasma physics, atomic clusters.Usually the RPA and QRPA are presented by making use of boson expansion techniques.If the one body transition operator is expressed linearly in bosons, the many body Hamiltonian with the two body interaction included becomes a quadratic polynomial in bosons 1

Equation of Motion Method to strongly correlated Fermi systems and Extended RPA approaches

“…In Ref. [95] the ground state is determined as a solution of a variational equation for the proton-neutron Lipkin model mapped onto the boson operators B † by using the Marumori method. The QRPA phonon operator…”