Pair correlations of non-uniform hard-sphere fluids in narrow slits and the mechanism of oscillatory solvation forces

The anisotropic pair-correlation functions for a hard-sphere fluid between hard walls have been calculated using the anisotropic Percus–Yevick (PY) approximation. The non-uniform fluid in the slit is in equilibrium with a hard-sphere bulk fluid of known density. Density profiles and pair distribution functions are displayed graphically for various slit widths and are used to give a detailed description of the mechanism for the oscillatory interaction between the walls and other structural properties of the fluid in the slit. A major goal in the discussion is a conceptual understanding of the physical factors that determine these properties.