The Yukawa potential was used for the attractive interaction of colloidal particles. The Duh-Mier-Y-Teran's equation of state (EOS) was used to express the Helmholtz free energy for the fluid phase. The first-order perturbation theory, the analytical expression of the radial distribution function (RDF) for the hard sphere potential in the FCC-crystal structure and the modified cell model were combined to establish the EOS for the solid phase. By using the established EOS and the renormalization-group (RG) theory, the fluid-fluid and fluid- solid equilibria for colloidal model systems were studied. Investigation shows that the attractive range parameter plays an important role in the phase transition of colloidal model systems. The obtained results agree well with the simulation data.

Key words: COLLOID, PHASE EQUILIBRIUM, REFORMING, LIQUID-SOLID EQUILIBRIUM, LIQUID-LIQUID EQUILIBRIUM