title: Nonlinear active micro-rheology in a glass-forming soft-sphere mixture.
abstract: We present extensive molecular dynamics computer simulations of a glass-forming Yukawa mixture, investigating the nonlinear response of a single particle that is pulled through the system by a constant force. Structural changes around the pulled particle are analyzed by pair correlation functions, measured in the deeply supercooled state of the system. A regime of intermediate force strengths is found where the structural changes around the pulled particle are small, although its steady-state velocity shows a strong nonlinear response. This nonlinear response regime is characterized by a force-temperature superposition principle of a Peclet number and anisotropic diffusive behavior. In the direction parallel to the force, mean-square displacements show anomalous superdiffusion in the long time limit. We analyze this superdiffusive behavior by means of the van Hove correlation function of the pulled particle. Perpendicular to the force, the driven particle shows diffusive behavior for all considered force strengths and temperatures. We discuss the dynamics perpendicular and parallel to the force in terms of effective temperatures.
authors.affiliation: Institut für Physik, Johannes-Gutenberg-Universität Mainz, Saarstraße 21, 55099 Mainz, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Winter
authors.forename: J
authors.initials: J
authors.lastname: Horbach
mesh_terms: D005898:Glass / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D010316:Particle Size; D012212:Rheology; D013499:Surface Properties; D013696:Temperature