Molecular dynamics simulations of water-ethanol mixtures. I. Composition trends in thermodynamic properties

Abstract

We explored the composition dependence of a rather comprehensive set of properties of liquid water-ethanol mixtures by using the isobaric-isothermal molecular dynamics computer simulations. The united atom non-polarizable model from the TraPPE data basis for the ethanol molecule combined with the TIP4P-2005 and SPC/E water models is considered. We restrict our calculations to atmospheric pressure, 0.1013 MPa, and room temperature, 298.15 K. Composition trends of the behavior of density, excess mixing volume, apparent molar volumes are described. On the other hand, the excess mixing enthalpy and partial molar enthalpies of species are reported. Besides, we explore the coefficient of isobaric thermal expansion, isothermal heat capacity, adiabatic bulk modulus and heat capacity at constant pressure. In addition, the self-diffusion coefficients of species, the static dielectric constant and the surface tension are described. We intend to get insights into peculiarities of mixing of species in the mixture upon changes of ethanol molar fraction. The quality of predictions of the models is critically evaluated by detailed comparisons with experimental results. Then, necessary improvements of the modelling are discussed.

Keywords

• molecular dynamics
• water-ethanol mixtures
• surface tension
• dielectric constant
• partial molar volumes