Isostructural solid-solid transition of (colloidal) simple fluids

Abstract

A variational approach based on the Gibbs-Bogoliubov inequality is used in order to evaluate the free energy of simple fuids described by a double-Yukawa pair potential. A hard-sphere reference fuid is used to describe the fuid phases, and an Einstein reference crystal to describe the solid phases. A part from the usual type of phase diagram, typical of atomic simple fuids with long-ranged attractions, we find two types of phase diagrams, specific to colloidal systems with intermediate and short-ranged attractions. One of the latter phase diagrams exhibits an isostructural solid-solid transition, which has not yet been observed experimentally