A SELF-CONSISTENT APPROACH TO A DENSITY-FUNCTIONAL FOR HOMOGENEOUS FLUIDS

A density functional, originally proposed by Rickayzen and Augousti fo r the study of the inhomogeneous hard sphere fluid, is generalized and applied to investigate the properties of the homogeneous hard sphere fluid. In principle, it is possible to determine simultaneously and se lf-consistently the two-particle direct correlation function, the equa tion of state and the strength of the excess free energy. In practice, it was found that, with the original form of excess free energy, conv ergence could not be achieved. With the generalized functional, howeve r, it is possible to derive self-consistently the direct correlation f unction and, at the same time, obtain agreement between the virial pre ssure, the functional pressure, and the compressibility Moreover, good agreement is obtained between the resulting pair distribution functio n and direct correlation function and the corresponding quantities obt ained from computer simulation At the largest reduced density studied, 0.90, there are small discrepancies which are most marked in the valu es of the direct correlation function near the origin.