Crossover between short- and long-time behavior of stress fluctuations and viscoelasticity of liquids.
An effective viscosity coefficient is introduced based on definite time averages of equilibrium stress fluctuations rather than stress correlations. Analysis of this quantity via molecular dynamics of a simple model liquid reveals a crossover between the expected short-time elastic and the long-time viscous behavior with increasing averaging time. The procedure allows us to extract the zero-rate shear viscosity when the averaging time becomes one order of magnitude larger than the relevant relaxation time. A relationship between this effective viscosity and the dynamic viscosities is established.
Hess
Siegfried
S
Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, Germany.
Kröger
Martin
M
Evans
Denis
D