On the temperature, pressure and composition effects in the properties of water-methanol mixtures. I. Density, excess mixing volume and enthalpy, and self-diffusion coefficients from molecular dynamics simulations

Abstract: We report the temperature, pressure and composition dependence of some basic properties of model liquid water-methanol mixtures. For this purpose the isobaric-isothermal molecular dynamics computer simulations are employed. Our principal focus is on the united atom non-polarizable UAM-I-EW model for methanol which was recently parametrized the paper by Garcia-Melgarejo et al. [J. Mol. Liq., 2021, 323, 114576], combined with the TIP4P/$\varepsilon$ water model. In perspective, the methanol model permits a convenient extension for other monohydric alcohols mixed with water. The behavior of density, excess mixing volume and enthalpy are described. Partial mixing properties are interpreted. Besides, we explored the trends of behavior of self-diffusion coefficients of the species of a mixture. The quality of predictions of the model is critically evaluated by detailed comparisons with experimental results. Various results are novel and provide new insights into the behavior of the mixtures in question at different temperatures and at high pressures. An improvement of the modelling necessary for further research is discussed.