Implicit finite-size effects in computer simulations

The influence of periodic boundary conditions (implicit finite-size effects) on the anisotropy of pair correlations in computer simulations is studied for a dense classical fluid of pair-wise interacting krypton atoms near the triple point. Molecular dynamics simulation data for the pair distribution function g(N)(r) = g(N)(r, theta, phi) of N-particle systems, as a function of radial distance r, polar angle theta, and azimuthal angle phi, are compared directly with corresponding theoretical predictions [L. R. Pratt and S. W. Haan, J. Chem. Phys. 74, 1864 (1981)]. For relatively small systems of N = 60, 80, and 108 atoms, significant angular variation is observed, which is qualitatively, and in several cases quantitatively, well predicted by theory. Finite-size corrections to the spherically-averaged radial distribution function g(N)(r), however, are found to be comparable to random statistical errors for runs of 10(5) time steps.