REVERSAL EFFECTS IN STOCHASTIC KINK DYNAMICS

We study collective regular and stochastic dynamics in a chain of harm onically coupled particles subjected to an on-site potential with two degenerate energy wells but with differing frequencies of small-amplit ude oscillations at their minima. We identify and study asymmetry-indu ced properties of a Peierls-Nabarro relief, kink-antikink interactions , and stochastic kink motion. In particular, we predict analytically a nd confirm numerically directed noise-induced soliton motion when the chain particles are driven by white and exponentially correlated noise . The difference of frequencies of oscillations in the vicinity of the wells is shown to be a sufficient condition for the existence of such a directed kink motion. We find that under certain conditions a rever sal of the soliton motion takes place; these conditions involve the no ise properties such as a critical correlation time or noise strength o r the presence of an external d.c, field. In particular, we find that above some critical value of temperature, the directed soliton transpo rt occurs against an applied d.c. field.