Liquid-vapor coexistence in square-well fluids: an RHNC study

We investigate the ability of the reference hypernetted-chain integral equation to describe the phase diagram of square-well fluids with four different ranges of attraction. Comparison of our results with simulation data shows that the theory is able to reproduce with fairly good accuracy a significant part of the coexistence curve, provided an extrapolation procedure is used to circumvent the well-known pathologies of the pseudo-spinodal line, which are more severe at reduced width of the attractive well. The method provides a useful approach for a quick assessment of the location of the liquid-vapor coexistence curve in this kind of fluid and serves as a check for the more complex problem of anisotropic 'patchy' square-well molecules.