Direct determination of the Tolman length from the bulk pressures of liquid drops via molecular dynamics simulations

Abstract

An expression for the difference in pressure between a liquid drop in equilibrium with its vapor Δp= pℓ - pv is derived from previous expressions for the components of the Irving-Kirkwood pressure tensor. This expression, as well as the bulk values of the pressure tensor, is then evaluated via molecular dynamics simulations of particles interacting through a truncated Lennard-Jones potential. We determine the Tolman length δ from the dependence of Δp on the equimolar radius. We determine the Tolman length to be δ=-0.10±0.02 in units of the particle diameter. This is the first determination of the Tolman length for liquid droplets via the pressure tensor route through computer simulation that is negative, in contrast to all previous results from simulation, but in agreement with results from density functional theory. In addition, we study the planar liquid-vapor interface and observe a dependence of the physical properties of the system on the system size, as measured by the surface area. © 2009 American Institute of Physics.