Professor Jerome K. Percus is supported by a grant from the Theoretical and Computational Chemistry Program to perform theoretical studies on model fluids which are subject to strong external forces such as those which occur in phase separations. This research is important for gaining a more complete theoretical understanding of fluid properties and the natural phenomenon of phase separation. Classical equilibrium fluids will be treated by free energy density functional extensions of local thermodynamics. Exactly solvable models, bulk information, exact restrictions, and the effects of non-local modes will be used as inputs for the model. Lattice gases will also be examined for the information they provide on feedback loops. Fermion fluid ground states will be handled by accurate representation of the kinetic energy functional, by extension of classical linear response techniques, and by momentum expansion based upon quantum phase space representation.