The influence of the attractive part of the potential in the Weeks-Chandler-Andersen perturbation theory is tested in a molecular dynamics calculation. The simulation was carried out at the triple point of a Lennard-Jones system. The differences (not negligible) in the radial distribution function permit the use of perturbation theory, because the thermodynamic properties show the usual linear behavior.

• Received 9 July 1984

DOI:https://doi.org/10.1103/PhysRevA.30.2781