9509743 Krotscheck Theoretical research will be conducted on strongly correlated many-body systems. Existing models will be applied to experiments and suggestions for new experiments will be made. In other areas where there are deficiencies in existing theoretical methods, the appropriate theory will be developed. Problems to be addressed include excitations of helium-four films and clusters; the description of adsorbed helium-three films and droplets, and in particular quasi-two-dimensional and layered electronic structures; and the formulation and implementation of a theory of multiparticle-multihole excitations analogous to the multi- phonon theory for bosons. %%% This theoretical research will deal with the formalism and applications of systems of many strongly interacting particles. Of particular interest are low temperature systems such as liquid helium which exhibit quantum properties. Connection will be made to recent experiments. ***