Phase equilibria of asymmetric hard sphere mixtures

The phase diagram of mixtures of hard spheres with additive diameters is st udied. The case of very different sizes is treated by means of mapping the two component system on a one component problem. In this monocomponent syst em large particles are explicitly considered, whereas the effects of the sm all component are included through an additional effective interaction pote ntial between large particles. The effective potential is used to analyze t he phase diagram of the mixture by means of computer simulation techniques. Results for the behavior at low density of small spheres seem to indicate that no fluid-fluid equlibria occur. On the other hand, the results show ho w this kind of mixture can exhibit equilibria between isostructural crystal line phases.