Brownian dynamics of a flexible polymer. Internal modes and quaiselastic scattering function

Abstract

Brownian Dynamics trajectories have been simulated by means of the Ermak and McCammon algorithm for Gaussian polymer chains of different lengths with hydrodynamic interactions. The results for relaxation times and dynamic scattering functions of chains with 2–20 statistical units are close to those calculated from the preaveraged Rouse–Zimm theory. The differences between both sets of results are slightly higher than the range of uncertainties of the simulation values (about 5% in most typical cases). Moreover, the simulated scattering functions have been fitted to sums of exponentials in order to extract translational diffusion coefficients and first relaxation times, following the Pecora procedure. The values obtained this way are in satisfactory agreement with the results directly calculated from the trajectories.