Interaction between kinks in coupled chains of adatoms

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Abstract
A Frenkel-Kontorova type of model is proposed to describe the dynamics of excess atoms (kinks) or vacancies (anti-kinks) in two parallel chains of atoms adsorbed on a crystal surface. Various dynamic processes with kinks belonging to different adatomic chains are considered within the framework of perturbation theory for non-linear waves, the local coupling between chains being a small parameter. In particular, the interaction energy of the kinks is calculated, and the collision of kinks in the presence of dissipation and a DC driving force is considered. It is demonstrated that two slow kinks can form a bound state due to dissipative energy losses, and the threshold value of the external force for this process is obtained. Different ways of exciting the internal oscillations of the bound state are discussed. Some radiative effects accompanying collision of two kinks belonging to different chains are investigated as well.