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 sha pe of the phase diagram in a system of particles that interact via a h ard-sphere potential plus an attractive Yukawa interaction; The gas-li quid phase diagram is evaluated both by Gibbs ensemble Monte Carlo sim ulation and reference hypernetted chain integral equation theory. An e stimate of the liquid-solid transition line was computed using a recen tly proposed one-phase entropic criterion with thermodynamic and struc tural input from the integral equation results. The overall agreement between theory and simulation is remarkable. Our results clearly indic ate that the;range of temperatures for which the liquid is stable shri nks as the interaction range decreases. At the same time, the gas-liqu id phase diagram tends to flatten out, in particular on the liquid sid e. For sufficiently short interaction ranges the system has no stable liquid phase.