A density functional study of superlattice formation in binary hard-sphere mixtures

A theoretical investigation of a binary mixture of hard spheres confirms that stable superlattice structures, with a complex long-range order of the AB 13 type, can form in these simple systems for intermediate values of the diameter ratio, in agreement with recent computer simulations and experimental studies of colloidal suspensions. It is shown that the larger entropy of mixing of the AB 13 structure relative to that of the competing structures is responsible for its thermodynamic stability.