Excess properties of aqueous mixtures of methanol: Simple models versus experiment

Molecular simulations on water-methanol mixtures were performed over the entire concentration range using primitive models that descend from realistic molecular models of both compounds. Since the primitive models reproduce, even semi-quantitatively, the structure of the pure compounds, the primary goal was to examine what thermodynamic features they are able to capture. Comparison of simulation data shows that the primitive and realistic models yield, qualitatively, the same behavior and that both fail to produce a minimum of the partial molar volume of methanol at low concentrations. Reasons for this failure along with details on the relation between specific intermolecular interactions and observed phenomena are discussed.