Molecular dynamics for discontinuous potentials

Abstract

A comparison of Monte Carlo results for hard dumbells with discontinuous molecular dynamics for vibrating hard dumbells is made in terms of structure and equation of state. The effect of the width of the confining well is studied in depth by comparing the molecular dynamics results with RISM and with an equation of state for hard dumbell fluids reported by Tildesley and Streett [7]. Calculations and arguments about an isolated molecule are also given. The comparison shows the equivalence of the two systems and that the influence of the width of the trapping well on the compressibility factor is dominated by the effective average elongation calculated by integration of the intramolecular g(r). RISM shows an interesting and qualitatively correct behaviour when solved for the same conditions as used in molecular dynamics, employing the intramolecular g(r)s obtained by the latter method.