Molecular dynamics simulation of the wave vector-dependent static dielectric properties of methanol–water mixtures

Publisher Website
Google Scholar
Abstract
The static wave vector-dependent dielectric properties of methanol–water mixtures at room temperature are investigated through molecular dynamics simulation. We report results for the transverse and longitudinal components of the permittivity tensors, as well as the short- and long-ranged portions of the Kirkwood g factors at small wave vectors k, calculated from the mean squared dipole densities for mixtures of different compositions. In addition, we have calculated dipolar symmetry projections h110(r) and h112(r) of the pair distribution functions for each mixture and determined the asymptotic behavior of the second projection at large distance r. We find that h110(r) and h112(r) as well as their contributions from different molecular pairs are strongly composition dependent, but that the resulting Kirkwood correlation factor is nearly independent of composition. We obtained the dielectric tensor ε(k) over a wide range of k using Fourier–Hankel transforms of h110(r) and h112(r). Our results indicate that this real space route is an attractive alternative approach to the static, k-dependent dielectric properties of polar liquids. The k-dependent transverse components of the permittivities obtained this way are in good agreement with the values calculated from the mean squared dipole densities. The longitudinal permittivities, on the other hand, show a less satisfactory agreement at small wave vectors due to inaccuracies in the numerical transforms.

This publication has 55 references indexed in Scilit: