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

摘要

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-fi 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 b~ 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.