The effect of potential truncation on the gas–liquid surface tension of planar interfaces and droplets

Abstract

Density functional theory is applied to study the properties of attracting hard-sphere fluids with different cutoffs of the Lennard-Jones potential. The cut-off dependence of the gas–liquid surface tension is not correctly described by a formula which depends only on temperature and critical temperature of the fluid. A better correlation with an explicit dependence on the cut-off radius is developed. The work of nucleus formation in gas–liquid nucleation is shown highly susceptible to potential truncation. The distance between the equimolar surface and the Gibbs surface of tension (δ) decreases for droplets if the potential is truncated. However, for very large droplets (more than 106 molecules) the truncation increases δ. The same holds for δ∞ (Tolman length) at planar interfaces.