Molecular dynamics simulation of ethanol/water mixtures for structure and diffusion properties

The structure and diffusion properties have been studied for ethanol/water mixtures at 298.15 K and atmospheric pressure by molecular dynamics (MD) simulation. The simulations were performed using a relatively simple rigid site-site model for ethanol and the TIP4P model for water. Partial radial distribution functions of pure water, pure ethanol and their binary mixtures are obtained to represent the microscopic structure properties. The self-diffusion coefficients and the mutual diffusion coefficients in the mixtures were calculated by the MD simulation. The self-diffusion coefficients of water and ethanol in the mixture are in qualitative agreement with the experimental data. The diffusion behavior of water in the aqueous solution is ascribed to the contributions of the "bound" water and the "free" water. The mutual diffusion coefficients keep fairly agreement with the experimental data. The effect of the distinct diffusion coefficient to the mutual diffusion coefficient has been evaluated and discussed. The simulation results suggest that the interaction potential models used is effective to describe the properties of the binary mixture. (c) 2005 Elsevier B.V. All rights reserved.