Are Global Renormalization Methods Capable of Locating Gas–Liquid Critical Points?

A global renormalization procedure used recently to calculate thermal volumetric properties near and to far from the critical point for two square-well fluids, widths 1.5 and 3.0, with accurately known critical points is here applied in an effort to determine where the critical point is located for three square-well fluids, widths 1.375, 1.75, and 2.0, for which accurate simulation data near the critical point are lacking. The present approach is suggested as an alternative to extrapolation methods that have been applied in the past and resulted in widely divergent predictions. A problem in the past has been knowing what to use as an effective critical point exponent, ;eff , for purpose of the extrapolation. The present renormalization calculations indicate that rather widely different behaviors of ;eff as a function of distance from the critical point can be expected for square wells of different width.