Kink's dynamics for a deformable substrate potential
Abstract
We study the static and dynamic properties of a kink in a chain of harmonically coupled atoms subjected to a deformable doublewell substrate potential. We treat intrinsically the lattice discreteness without approximation and show that in some deformationparameter ranges each period of the PN (PeierlsNabarro) potential consists of two wells whose minima are located respectively on a lattice site and midway between two adjacent sites of the chain. In some other parameter ranges each period of the PN potential posseses a single well whose minimum is located either on a lattice site or midway between two adjacent lattice sites. We examine the kink's dynamics by using a multiplecollectivevariable treatment, that is, we derive the exact equations of motion for the collective variables X and Y  which describe respectively the centerofmass mode and the internal mode of the kink. We numerically solve the collective variable equations of motion for the trapped and untrapped regimes of the discretekink motion, and show that the presence of a nonlinear internal mode makes a contribution of particular importance in the discretekink's dynamics. Indeed, we show that during its untrapped regime, the discrete kink can undergo one or more temporary trappings and even a reflection back over several PN wells, and relate such behaviours to the effects of the excitations of the internal mode of the kink.
 Publication:

Physica D Nonlinear Phenomena
 Pub Date:
 January 1994
 DOI:
 10.1016/01672789(94)900159
 Bibcode:
 1994PhyD...70..217T