Phase diagrams of hexadecane–CO2 mixtures from histogram-reweighting Monte Carlo Original Research Article

We investigate the phase behaviour of a hexadecane–CO2 mixture with a coarse-grained off-lattice model. CO2 is described by a single Lennard–Jones sphere and hexadecane by a chain of five LJ monomers with additional FENE interactions. Interaction parameters are derived from the critical points of pure hexadecane and CO2 using a modified Lorentz–Berthelot mixing rule for the mixture. Simulations are based on grand-canonical histogram-reweighting Monte Carlo. A method to calculate interfacial tensions is described in detail. The analysis of the model includes simulated phase diagrams and interfacial tensions for pure hexadecane and CO2 as well as a general phase diagram with complete critical lines for their mixture. We find evidence that a small change of interaction parameters between different species leads to qualitatively different phase behavior.