ROLE OF THE INTERACTION RANGE IN THE SHAPING OF PHASE-DIAGRAMS IN SIMPLE FLUIDS - THE HARD-SPHERE YUKAWA FLUID AS A CASE-STUDY

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.