The connection between hydrogen bonding between water and acetonitrile in determining the microheterogeneity of the liquid mixture is examined using NPT molecular dynamics simulations. Mixtures for six, rigid, three-site models for acetonitrile and one water model were simulated to determine the amount of water-acetonitrile hydrogen bonding. None of the six mixtures were able to reproduce the expermental estimates of hydrogen bonding derived from Raman scattering of the CN stretch band or from NQR measurements. Some simple modifications of the acetonitrile model parameters produced hydrogen-bonding re-sults consistent with experiment for all six models. Only two of the modified models reproduced the density of the mixtures. The self-diffusion coefficients of liquid acetonitrile provided a final winnowing of the modified models. That model is provisionally recom-mended for simulations of water-acetonitrile mixtures.
Citation: Journal of Physical Chemistry B
Pub Type: Journals
acetonitrile, hydrogen bond, interaction potential, microheterogeneity, mixture molecular dynamics, pair correlation, water