Suchergebnisse

We study the possibility of kink motion induced by pure ac driving in damped nonlinear lattices, focusing on the Frenkel-Kontorova and Toda models. Numerical simulations of the Frenkel-Kontorova model show no evidence for steady kink motion. We point out that momentum-balance in addition to energy-balance arguments are needed to understand the translation of the collective excitation. Finally, our result is discussed in view of related theoretical predictions and numerical simulations. ; Support from a MEC/Fulbright grant, from DGICyT (Spain) under Project No. PB92-0248, and from the European Union Network ERBCHRXCT930413. Work at Zaragoza was supported by DGICyT (Spain) under Project No. PB92-0361, and by the European Union (NETWORK on Nonlinear Approaches to Coherent and Fluctuating Processes in Condensed Matter and Optical Physics). Work at Los Alamos was performed under the auspices of the U.S. Department of Energy. ; Publicado

A model of surface growth given by a two-dimensional discrete, driven, damped sine-Gordon equation is studied using Langevin dynamics. Our large-scale simulations show that the equilibrium Kosterlitz-Thouless roughening transition splits into two crossovers (or transitions) under the external force of, e.g., vapor-surface chemical potential difference. Three different regimes are characterized in terms of roughness, growth rate, and height-height correlations-the onset of a rough phase is accompanied by the suppresion of oscillatory growth. Our results are interpreted consistently within a renormalization group framework. We discuss the generality of our conclusions and propose specific comparisons with experiments ; Partially supported by DGICyT (Spain) Grant No. PB92-0248, by MEC (Spain)/Fulbright, and by the European Union Network ERBCHRXCT930413. Work at Los Alamos is performed under the auspices of the U.S. DOE. ; Publicado