Simulation studies of nearest-neighbor distribution functions and related structural properties for hard-sphere systems

Molecular dynamics simulations have been carried out to investigate nearest -neighbor distribution functions and closely related quantities for the sys tem of hard-spheres. The nearest-neighbor distribution function and the exc lusion probability function were computed to examine the density dependence on the structural 'void' and 'particle' properties. Simulation results wer e used to access the applicabilities of various theoretical predictions bas ed on the scaled-particle theory, the Percus-Yevick equation, and the Carna han-Starling approximation. For lower density systems the three different a pproximations give the nearest-neighbor distribution functions which are ve ry close to one another and also to the resulting simulation data. Among th ose theoretical predictions, the Carnahan-Starling approximation gives rema rkably good agreement with the simulation data even for higher density syst ems. Also calculated is the nth moment of the nearest-neighbor distribution functions, in which the corresponding length scale is directly related to the measurement of the characteristic pore-size distribution.