The phase behavior of a hard sphere chain model of a binary n-alkane mixture

Monte Carlo computer simulations have been used to study the solid and flui d phase properties as well as phase equilibrium in a flexible, united atom, hard sphere chain model of n-heptane/n-octane mixtures. We describe a meth odology for calculating the chemical potentials for the components in the m ixture based on a technique used previously for atomic mixtures. The mixtur e was found to conform accurately to ideal solution behavior in the fluid p hase. However, much greater nonidealities were seen in the solid phase. Pha se equilibrium calculations indicate a phase diagram with solid-fluid phase equilibrium and a eutectic point. The components are only miscible in the solid phase for dilute solutions of the shorter chains in the longer chains . (C) 2000 American Institute of Physics. [S0021-9606(00)50805-8].