Application of density functional perturbation theory to pure fluid liquid-vapor interfaces.

Common density functional theories often use the so-called mean-field approximation to the attractive term of the free energy, which is not accurate when compared with molecular dynamics simulations. We applied a modification of this attractive free energy term of a local density functional approach where an analytical representation of the radial distribution function is taken into account. A cutoff Lennard-Jones-12-6 potential, divided according to the Weeks-Chandler-Andersen prescription, is used as the intermolecular interaction force model. This density functional perturbation approach gives the correct phase quilibrium and predicts a surface tension in excellent agreement with recent molecular dynamics simulations. The surface tension of some pure simple fluids is predicted from an intrinsic contribution, obtained by the modified density functional perturbation theory, plus contributions due to capillary wave roughening of the surface. The respective Lennard-Jones potential parameters were obtained from fitting to saturated liquid densities of the pure fluids. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]