Anomalous Diffusion and Relaxation of Collapsed Polymer Chains

Time-dependent displacement of monomers and the centre-of-gravity motion of a polymer chain at various temperatures below the theta-temperature are studied by Monte Carlo simulation of an off-lattice model. While inner monomers diffuse Rouse-like, ⟨[ r i ( t ) − r i (0)] 2 ⟩ ∝ t 1/2 , the centre of mass exhibits pronounced anomalous diffusion, ⟨[ r c.m. ( t ) − r c.m. (0)] 2 ⟩ ∝ t a , where the exponent a seems to depend on temperature. The resulting anomalous dependence of the relaxation times on chain length is discussed in terms of scaling ideas. A possible relation to a glasslike freezing in of the collapsed globules is pointed out.