Frequency-dependent viscosity of linear, ring, and star Gaussian chains with fluctuating hydrodynamic interactions

Numerical values for the stress correlation function and the frequency-dependent complex viscosity of linear, ring, and star Gaussian chains with fluctuating hydrodynamic interactions have been obtained from Brownian dynamics simulation. Numerical procedures to calculate these properties (inspired by the previous work of Fixman) are devised. The numerical values are significantly smaller than those obtained with preaveraged hydrodynamic interactions (employed in the standard theories), especially in the low frequency region. Differences are very important (about 100%) for the star chains. These differences tend to decrease for higher frequencies but are still remarkable in the intermediate frequency region (the high frequency predictions for the Gaussian model are not of practical interest).