论文标题
空间解决的原子尺度摩擦：理论和模拟
Spatially resolved atomic-scale friction: Theory and Simulation
论文作者
论文摘要
我们通过绿色kubo关系和经典的分子动力学模拟分析了在原子尺度表面滑动的小探针粒子上施加的摩擦力。我们发现，在原子尺度上，摩擦张量可以随着位置和滑动方向的函数而大幅变化。绿色 - 库博关系得出了作用在探针上的力的时间相互协方差的平衡模拟的位置和方向依赖性。我们意外地发现，能量耗散的位置和方向依赖性与（更简单的）静态力协方差有关，尤其是在探针仅在探针中占据表面颗粒的极限。相比之下，探针所经历的（自由）能量景观通常不是局部耗散的良好指标。我们还讨论了利用本地和方向分辨的摩擦张量的优化策略。这使我们能够找到最佳的滑动路径和速度协议，例如，在给定时间内在表面上的两个点之间最小化的能量耗散。
We analyze the friction force exerted on a small probe particle sliding over an atomic-scale surface by means of a Green-Kubo relation and classical Molecular Dynamics simulations. We find that, on the atomic scale, the friction tensor can drastically vary as a function of position and sliding direction. The Green-Kubo relation yields this positional and directional dependence from equilibrium simulations of the time dependent covariance of force acting on the probe. We find, unexpectedly, that the positional and directional dependence of energy dissipation is related to the (much simpler) static force covariance, especially in the limit where the probe only mildly perturbs the surface particles. In contrast, the (free) energy landscape experienced by the probe is in general not a good indicator of local dissipation. We also discuss optimization strategies making use of the locally and directionally resolved friction tensor. This enables us to find optimal sliding paths and velocity protocols, e.g., minimizing energy dissipation, between two points on the surface in a given time.
