Nonlinear friction of a damped dimer sliding on a periodic substrate

• Autor(a) principal: Goncalves, Sebastian
• Data de Publicação: 2004
• Outros Autores: Kenkre, V. M., Bishop, A. R.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/104293
• topic: Física da matéria condensada; Dinâmica molecular; Fricção

The nonlinear sliding friction of a dimer over a substrate is studied within a one-dimensional model, consisting of a vibrating dimer (two masses connected by a spring), internally damped, sliding over a sinusoidal potential. Molecular dynamics simulations show that the friction force has an approximate v−3 dependence if the velocity is sufficiently large, and that there is a striking periodic variation of the proportionality coefficient with the ratio of the length of the dimer to the substrate wavelength. The nonlinear velocity dependence was predicted earlier for a Langevin model of an adsorbed layer in the presence of strong external force. We study it here in detail in the transient regime and without external force. We obtain the dependence on key parameters (internal dissipation, dimer mass, substrate corrugation, and length ratio), and examine the validity of the friction law. A semianalytical expression is suggested which confirms the numerical observations in the high-velocity regime.