  The aim of this paper is to compare results from lattice-Boltzmann and
Brownian dynamics simulations of linear chain molecules. We have systematically
varied the parameters that may affect the accuracy of the lattice-Boltzmann
simulations, including grid resolution, temperature, polymer mass, and fluid
viscosity. The effects of the periodic boundary conditions are minimized by an
analytic correction for the different long-range interactions in periodic and
unbounded systems. Lattice-Boltzmann results for the diffusion coefficient and
Rouse mode relaxation times were found to be insensitive to temperature, which
suggests that effects of hydrodynamic retardation are small. By increasing the
resolution of the lattice-Boltzmann grid with respect to the polymer size,
convergent results for the diffusion coefficient and relaxation times were
obtained; these results agree with Brownian dynamics to within 1--2%.
