Structure and dynamics of the interface between a binary hard-sphere crystal of NaCl type and its coexisting binary fluid

Abstract

Molecular-dynamics simulations are performed to study the [100] and [111] orientations of the crystal-melt interface between an ordered two-component hard sphere with an NaCl structure and its coexisting binary hard-sphere fluid. The diameter ratio of the two types of hard spheres making up the mixture is α=0.414. This work complements our earlier interface simulations [J. Chem. Phys. 116, 3410 (2002)] for the same diameter ratio at lower pressures where the smaller component is immiscible in the solid and the fluid mixture coexists with a pure fcc crystal of large particles. Density profiles and diffusion coefficient profiles are presented for the AB interfacial system. We find that for this system, the transition from crystallike to fluidlike behavior of both the density and diffusion constant profiles occurs over a narrower region than that seen in our previous studies of the fcc/binary fluid system. But similar to what was found in the fcc/binary fluid interface the transition region for the large particle diffusion constant is shifted about 1.0σA toward the fluid phase relative to that for the small particles.