Role of the interaction range in the shaping of phase diagrams in simple fluids. The hard sphere Yukawa fluid as a case study

Abstract

We have investigated the influence of the interaction range on the shape of the phase diagram in a system of particles that interact via a hard-sphere potential plus an attractive Yukawa interaction. The gas–liquid phase diagram is evaluated both by Gibbs ensemble Monte Carlo simulation and reference hypernetted chain integral equation theory. An estimate of the liquid–solid transition line was computed using a recently proposed one-phase entropic criterion with thermodynamic and structural input from the integral equation results. The overall agreement between theory and simulation is remarkable. Our results clearly indicate that the range of temperatures for which the liquid is stable shrinks as the interaction range decreases. At the same time, the gas–liquid phase diagram tends to flatten out, in particular on the liquid side. For sufficiently short interaction ranges the system has no stable liquid phase.