FLUCTUATIONS IN AN EQUILIBRIUM HARD-DISK FLUID - EXPLICIT SIZE EFFECTS

Explicit size corrections in the calculation of the fluctuations in th e number of particles in a finite subvolume of a hard-disk fluid compo sed of a fixed number of particles are considered. The size correction s are obtained on the basis of a Taylor series expansion of the pair d istribution function of the N-particle system in powers of 1/N. Analyt ical density dependent expressions are obtained at low density. These expressions show that not only explicit size effects (due to considera tion of a fixed number of particles) but also edge effects that result from considering a finite subvolume must be taken into account. A gen eral density dependence study is also reported by relating the relativ e fluctuation in the number of particles to the equation of state. Num erical results for the Henderson equation of state are obtained. These theoretical results are compared with Monte Carlo computer simulation results. (C) 1997 American Institute of Physics.