Institut für Physik, Johannes-Gutenberg-Universität Mainz, Saarstraße 21, 55099 Mainz, Germany.
J Chem Phys. 2013 Mar 28;138(12):12A512. doi: 10.1063/1.4770335.
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.
我们呈现了对玻璃形成的 Yukawa 混合物的广泛分子动力学计算机模拟，研究了通过恒力在系统中被拉动的单个粒子的非线性响应。通过在系统的深度过冷状态下测量的对关联函数，分析了被拉动粒子周围的结构变化。在中间力强度的范围内，尽管其稳态速度表现出强烈的非线性响应，但被拉动粒子周围的结构变化很小。该非线性响应区域的特征在于 Peclet 数和各向异性扩散行为的力-温度叠加原理。在与力平行的方向上，均方位移在长时间极限下表现出反常的超扩散。我们通过拉动粒子的 van Hove 相关函数来分析这种超扩散行为。垂直于力的方向，对于所有考虑的力强度和温度，驱动粒子都表现出扩散行为。我们根据有效温度讨论了垂直和平行于力的动力学。
