A functional derivative approach to thermodynamically self-consistent radial distribution functions

A new approximation for the radial distribution function is presented which ensures consistency between the pressure and compressibility equations. The approximation is applied to the hard sphere system for calculation of the first six virial coefficients and evaluation of the pressure up to 0·7 of the closepacking density. The results are similar to an earlier self-consistent theory and show substantial improvement over previous theories lacking internal consistency. An upper bound which limits the degree of short-range order possible in the fluid state is discussed.