In statistical mechanics, the distribution of interparticle separations determines the radial distribution function .
This Demonstration shows the radial distribution function of a three-dimensional liquid composed of identical hard spheres of diameter , making use of the exact solution of the Percus–Yevick integral equation [2, 3]. You can vary the packing fraction of the liquid, that is, the fraction of the total volume occupied by the spheres themselves. For a packing fraction greater than about 0.49, the corresponding can be regarded as that of a metastable liquid since the true stable phase is a crystal.
The Demonstration also includes three functions directly related to the radial distribution function : the structure factor , the direct correlation function , and the bridge function .