Composition and temperature dependence of the dielectric constant of 1-propanol/water mixtures: Experiment and molecular dynamics simulations

The dielectric constant of pure 1-propanol, as well as of its mixtures with water, has been determined experimentally, as a function of temperature and composition. In parallel, molecular dynamics simulations, using united atom (UA) and all atom (AA) model potentials for the alcohol, have been performed, in order to calculate the same quantity for the same mixtures and at identical temperatures. Two water models were used, SPC/E and TIP4P/ε. The calculations were able to capture the trends of changes for the dielectric constant with temperature and composition. It has been shown that as water concentration grows, the actual values of calculated static dielectric constant get somewhat farther from the measured data when the SPCE water model is applied. Targeted modifications of the UA interatomic potentials of the alcohol, in combination with the TIP4P/ε water model, provide quantitative reproduction of the measured dielectric constant values over the entire composition and temperature ranges.