PHASE-STABILITY OF BINARY NONADDITIVE HARD-SPHERE MIXTURES - A SELF-CONSISTENT INTEGRAL-EQUATION STUDY

We have tested the capabilities of a new self-consistent integral equa tion, closely connected with Verlet's modified closure, for the study of fluid-fluid phase separation in symmetric non-additive hard-sphere mixtures. New expressions to evaluate the chemical potential of mixtur es are presented and play a key role in the construction of the phase diagram. The new integral equation, which implements consistency betwe en virial and fluctuation theorem routes to the isothermal compressibi lity, together with chemical potential and virial pressure consistency via the Gibbs-Duhem relation, yields a phase diagram which especially at high densities agrees remarkably well with the new semi-Grand Ense mble Monte Carlo simulation data also presented in this work. Deviatio ns close to the critical point can be understood as a consequence of t he inability to enforce virial-fluctuation consistency in the neighbor hood of the spinodal decomposition curve. (C) 1996 American Institute of Physics.