The problem of surface tension definition of nanodrops

Abstract

The dependence of the surface tension of Lennard-Jones liquid small drops on the radius and temperature has been calculated by the molecular dynamics method. It is found that the mechanical surface tension is different from the Gibbs's surface tension for drops of 50-2000 molecules and is equal to it for drops of more than 2000 molecules. It is shown that both the mechanical and Gibbs's surface tensions decrease with the decrease of the equimolar radius of the drop and reach zero at the same R0 depending on temperature. The radii of tension also reach zero at the same R0. The dependence of the ratio of the mechanical surface tension of the drop to the surface tension of the flat surface liquid-vapor (ρ/ρ∞) on the ratio of the equimolar radius of the drop to R0 is a universal function. The limit of applicability of the surface tension concept to the small radii droplets changes from 50 to 300 molecules depending on temperature. © 2010 The Surface Science Society of Japan.