Structure and dynamics of water in aqueous methanol

We have performed classical molecular dynamics simulations to investigate the structure and dynamics of water clusters in aqueous methanol across a range of solution compositions. Investigation of the effect of different model potentials and cluster membership criteria indicates that the qualitative trends in cluster size distributions are preserved. Characterization of the water molecules on the interior of such clusters using a tetrahedral order parameter previously used to study pure water suggests that they are over-structured compared to the pure liquid for a broad range of cluster sizes and at different compositions. Calculation of the hydrogen-bond dynamics indicates that the water-water hydrogen-bonds in the solution are longer lived than those in the pure liquid for all solutions studied and increase almost linearly as a function of methanol concentration.