Calculation of the entropy and the chemical potential of fluids and solids from the radial free-space distribution function

Abstract

A method for calculating the entropy and the chemical potential of fluids and solids from the radial free-space distribution function (RFSDF) is proposed. The free volume is obtained from the RFSDF by eliminating the arbitrary definition of a cell and the imposition of a cut-off distance that were used in the theory of the previous paper. The RFSDF has a constant value (defined here as y-infinity at distances larger than the radius of the cell: y-infinity is calculated by averaging the RFSDFs at these larger distances. This new method overcomes the usual difficulties appearing in the calculation of the free energy, and leads to results that are comparable to those obtained by other methods.