VAPOR-LIQUID COEXISTENCE FOR PURELY REPULSIVE POINT-YUKAWA FLUIDS

Using a simple mean-field theory and MC simulations we demonstrate the existence of a vapour-liquid transition in a fluid with purely repuls ive Yukawa pair interactions and a density-dependent screening paramet er. This transition does not fit into the classical Van der Waals pict ure, as the mechanism of liquid condensation is not caused by long-ran ged attractions. The phase separation is, instead, driven by the enhan ced screening at higher densities, which leads to ideal-gas behaviour at sufficiently high densities. A fluid at intermediate densities can thus reduce its free energy by separating into a dilute vapour and a h igh-density liquid.