INHOMOGENEOUS HARD HOMONUCLEAR MOLECULES

A review is given of some features of theories for inhomogeneous fluid s of nonspherical molecules that take as input the direct correlation function of the corresponding homogeneous system. Two different method s are described for defining the structure of hard homonuclear molecul es close to a hard planar wall. A spherical harmonics expansion (SHE) within the integral equation (IE) method is presented and, for compari son, a version of density functional theory for orientable hard bodies . In both cases the Pynn-Lado model is employed and a comparison is ma de with Monte Carlo data. The results indicate that for hard molecules the IE approach does not always capture the effects of orientation du e to the characteristics of the SHE for the step function. This disadv antage is particularly true in the case of the orientationally average d density profile.