Solid–liquid phase equilibria for mixtures containing diatomic Lennard–Jones molecules

Solid—liquid phase diagrams are calculated for systems containing pure Lennard–Jones dumbbell molecules and their mixtures. We begin by calculating the equations of state for systems containing C2H6, CO2 and F2, all of which are modeled by a two-center Lennard–Jones potential for linear diatomic molecules. We then use the Frenkel–Ladd thermodynamic integration method to calculate the free energies. The equations of state and the free energies are used to obtain solid–liquid coexistence points which are needed to start the Gibbs–Duhem integration. The solid–liquid phase equilibria for pure C2H6, CO2 and F2 and binary mixtures of Lennard–Jones dumbbells are predicted using the Gibbs–Duhem integration method. We investigate the effects of molecular size and intermolecular attractions on the solid–liquid phase diagrams of binary Lennard–Jones mixtures.