Monte Carlo simulations for the phase behavior of symmetric nonadditive hard sphere mixtures

Computer simulation results are presented for the phase behavior of a symmetric binary mixture of nonadditive hard spheres. In this model, the hard sphere diameters are given by $σAA=σBB=λd$ and $σAB=d.$ At high densities and for small enough λ, this hard sphere mixture exhibits a fluid–fluid phase separation into an A-rich and a B-rich phase. Semigrand ensemble simulations are performed for the critical point and the phase behavior of this model for various values of λ. The results for the critical density are significantly different from previous simulation estimates. A comparison of our simulation results to existing theories shows that none of the theories are accurate for the location of the critical point, over the entire range of λ.