Recurrence phenomena in soliton propagation in a lattice with impurities

Abstract
The scattering of a soliton from a mass impurity in a Morse or Toda one-dimensional lattice with periodic boundary conditions is studied numerically. The energy of the soliton as a function of time exhibits either a fast decay (chaotic behaviour) or a recurrence, or an intermediate 'metastable' behaviour, which consists of a time period when recurrence takes place, followed by a fast decay. A model is developed to explain the recurrence and predict the recurrence time. A semiquantitative argument is also presented to explain the 'metastable' case. Finally the generality of this type of behaviour is discussed.