MOLECULAR DYNAMICS SIMULATIONS OF DIELECTRIC PROPERTIES OF DIMETHYL SULFOXIDE - COMPARISON BETWEEN AVAILABLE POTENTIALS

摘要

We present a molecular dynamics simulation study of the orientational correlations of molecular dipoles and dielectric properties of a series of recently proposed models for liquid dimethyl sulfoxide. The dipole-dipole correlations, as measured by the dipolar symmetry projections h(110)(r) and h(112)(r), sire very similar for the models with four partially charged sites, but differ somewhat for the potential with no charges on the methyl groups. The effects of the charges on the methyl sites upon the local ordering of the molecular dipoles are discussed by comparing the h(110)(r) projections for two models which differ only in their site-charge assignments. The Kirkwood g factors for the simulated force fields turn out all greater than unity, in disagreement with some experimental estimates. The dielectric constants, however, are in good agreement with reported experimental data. In addition, we discuss the wave vector (k) dependence of the longitudinal static dielectric responses and also the single-particle molecular reorientation dynamics,which is found to differ from model to model. Likely consequences of that To the dielectric relaxation of these models are briefly discussed. (C) 1997 American Institute of Physics. [References: 58]