Simulational Tests of the Rouse Model

An extensive review of literature simulations of quiescent polymer melts is given, considering results that test aspects of the Rouse model in the melt. We focus on Rouse model predictions for the mean-square amplitudes [Formula: see text] and time correlation functions [Formula: see text] of the Rouse mode [Formula: see text]. The simulations conclusively demonstrate that the Rouse model is invalid in polymer melts. In particular, and contrary to the Rouse model, (i) mean-square Rouse mode amplitudes [Formula: see text] do not scale as [Formula: see text] , N being the number of beads in the polymer. For small p (say, [Formula: see text]) [Formula: see text] scales with p as [Formula: see text]; for larger p, it scales as [Formula: see text]. (ii) Rouse mode time correlation functions [Formula: see text] do not decay with time as exponentials; they instead decay as stretched exponentials [Formula: see text]. [Formula: see text] depends on p, typically with a minimum near [Formula: see text] or [Formula: see text]. (iii) Polymer bead displacements are not described by independent Gaussian random processes. (iv) For [Formula: see text] , [Formula: see text] is sometimes non-zero. (v) The response of a polymer coil to a shear flow is a rotation, not the affine deformation predicted by Rouse. We also briefly consider the Kirkwood–Riseman polymer model.