Diffusion of overdamped classical solitons

We study the diffusion and deformation of classical solitons coupled to the rmal noise. The diffusion coefficient for kinks in the phi(4) theory is pre dicted up to the second order in kT. The prediction is verified by numerica l simulations. Multiskyrmions in the vector O(3) sigma model are studied wi thin the same formalism. Thermal noise results in a diffusion on the multis oliton collective coordinate space (moduli space). There are entropic force s which tend, for example, to bind pairs of solitons into bi-solitonic mole cules. (C) 1999 Elsevier Science B.V.