DENSITY-FUNCTIONAL STUDY OF SOLID-TO-SOLI D ISOSTRUCTURAL TRANSITIONSIN COLLOIDAL CRYSTALS

We apply density-functional theory to study the expanded-FCC-to-conden densed-FCC transition of a system of hard, spherical particles with a short-ranged square-well and Yukawa attractive interaction, predicted recently by the simulations of Bolhuis and Frenkel(1). Our approach is based on a non-perturbative treatment of the repulsive hard-care parr of the potential, using the modifyed weighted density approximation ( MWDA), and a mean-field approximation for the attractive pare. This th eoretical treatment describes the existence of an isostructural solid- to-solid transition terminating at a critical point, in quantitative a greement with the the simulation results.