Quantum-classical correspondence for isolated systems of interacting particles: Localization and ergodicity in energy space

Generic properties of the strength function (local density of states (LDOS)) and chaotic eigenstates are analyzed for isolated systems of interacting particles. Both random matrix models and dynamical systems are considered in the unique approach. Specific attention is paid to the quantum-classical correspondence for the form of the LDOS and eigenstates, and to the localization in the energy shell. A new effect of the non-ergodicity of individual eigenstates in the deep semiclassical limit is briefly discussed.