Kinks motion and underdamped dc-driven dynamics of atomic monolayers

A multi-step dynamical phase transition from the locked to the running state of atoms in response to a de external force is studied by molecular dynamics simulations of the generalized Frenkel-Kontorova models in the underdamped limit. We show that the hierarchy of depinning transition recently reported [Braun et al., Phys. Rev. Lett. 78 (1997) 1295] strongly depends on the friction. In the present study we consider (i) a generalized FK model with highly anisotropic quasi-one-dimensional rectangular potential, and (ii) an isotropic triangular system, where the interactions between neighboring "channels" play an important role in the dynamics. Copyright (C) 1998 Elsevier Science B.V.