Monte Carlo calculation of phase equilibria in ternary systems

Results are presented for some coherent and incoherent phase diagrams for ternary systems, which have been obtained by Monte Carlo simulations. An appropriate computer algorithm, which permits the chemical potentials of the particles and the lattice gas pressure of the equivalent binary lattice gas in two separate phases to be equalised, is described. A comparison is made with phase diagrams for the same systems but obtained by using the point, pair and tetrahedron cluster variation approximations. It is found that, for the same values of the interaction energy and temperature used, the phase diagrams obtained by using the Monte Carlo method are significantly different from those obtained by using the point and pair cluster variation approximations. The phase diagram obtained by using the tetrahedron cluster variation approximation, however, is found to be only slightly different from that obtained in the present work.