Phase diagram of hard spheres confined between two parallel plates

Abstract

A hard sphere system confined between two parallel hard plates is investigated theoretically. Using extensive Monte Carlo computer simulations, the phase diagram is calculated for the whole range of densities and plate separations ranging from one to two particle diameters. There occurs a strong first-order fluid freezing transition and both very weak and strong discontinuous phase transitions between different crystal structures, namely, layered, buckled, and rhombic crystals. The results are compared with predictions from free volume theory, and a semiquantitative agreement is found. All predicted transitions should be experimentally observable in confined suspensions of sterically stabilized or highly salted charged colloidal particles.