Molecular reorientation and shear viscosity in dense liquids

The viscosity dependence of reorientation correlation times τϑ for a number of neat liquid monosubstituted benzenes and several symmetric top molecules has been analyzed in terms of Hu and Zwanzig’s hydrodynamic slip limit and also the parameter κ introduced by Kivelson. The slip limit predictions are improved by introducing a weighting factor which emphasizes molecular shape. The analysis of our high pressure data shows that the parameter κ is independent of pressure and temperature, in agreement with the results of other studies. The coupling between translational and rotational motions as characterized by κ is dominated by the molecular shape.