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|Type:||Artigo de periódico|
|Title:||Static dielectric properties of a model for liquid DMSO|
|Abstract:||Molecular dynamics simulations are used to study the wave vector (k) dependent static dielectric properties of a recently proposed model (H. Liu, F. Muller-Plathe and W. F. van Gunsteren, 1995, J. Amer. chem. Soc., 117, 4363) for liquid dimethyl sulphoxide (DMSO). Room temperature results are given for the real-space orientational pair correlations h(110)(r) and h(112)(r), for the k-dependent short- and long-ranged generalized Kirkwood g factors, g(K)(S)(k) and g(K)(L)(k), and for the k-dependent transverse and longitudinal components of the dielectric permittivity tensor, epsilon(T)(k) and epsilon(L)(k), over wide ranges of k values. These k-dependent quantities have been obtained from the Fourier-Hankel transforms of the projections h(110)(r) and h(112)(r). The function h(110)(r) reveals that the relative orientation between neighbouring molecules may result from dipolar forces, and that the local order of the molecular dipoles is consistent with the results from other studies on DMSO. The system's shape-independent Kirkwood g factor calculated from the k --> 0 limit of g(K)(S)(k) is 1 . 6, and using this value in the Kirkwood relation yields epsilon(0) = 44 for the system's dielectric constant. The asymptotic behaviour of h(112)(r) obtained from an auxiliary simulation on a 2048 molecules system yields similar estimates for epsilon(0). The calculated values for the model's Kirkwood g factor and dielectric constant are in very good agreement with experimental data at room temperature. In addition, calculations were made of the contributions to epsilon(T)(k) and epsilon(L)(k) from the molecular spatial charge distribution under several different approximations. These contributions are essential for a correct characterization of the k-dependent dielectric properties of the model at finite values of k.|
|Editor:||Taylor & Francis Ltd|
|Appears in Collections:||Artigos e Materiais de Revistas Científicas - Unicamp|
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