Dynamics of the sine-Gordon chain

Using a molecular-dynamics technique, we studied some nonequilibrium properties of the sine-Gordon chain in one space dimension. We found a t43 long-time tail in the mean-square displacement, and self-diffusion is traced back to the motion of kink solitons. It is shown that the propagation of these kinks gives rise to a new excitation branch. © 1978 The American Physical Society.