Extended Time Scale Simulation Studies of Nanoscale Friction

该奖项资助应用原子尺度模拟研究纳米级摩擦物理学的新技术的开发。这些技术的目的是延长模拟的时间尺度，目前模拟的时间尺度被限制在1微秒以内。 这使得目前的方法不适合模拟滑动速率明显低于0.1 m/s的过程。 为了比较，AFM实验和MEMS滑动发生在10-6？10-9 m/s. 这些模拟方法也将扩展到固有的非平衡模拟。 预计这种长时间的非平衡模拟将是有用的测试理论的摩擦对模拟，其中一个单一的粗糙接触是现实modeled.The项目的目标是扩大我们的知识，关于纳米尺度上的摩擦的基本物理和化学。 这些知识对于设计微和纳米机电设备（MEMS/NEMS），解释原子力显微镜（AFM）的表面表征结果以及开发精密应用中润滑的有效方法至关重要。调查将使过渡的摩擦响应相对于滑动速率和温度的分析。这些方法还将为研究吸附物（如碳氢化合物）的影响以及表面化学对摩擦和磨损的影响奠定基础，并有可能扩展到各种其他系统，包括断裂、疲劳、粘附和其他非平衡材料过程的研究。 该项目将资助一名研究生和博士后研究员。 调查员还将与JHU MRSEC和PREM赠款活动的外联活动协调，每年夏天将一名代表性不足的少数民族学生带入实验室，以获得与PI和研究生密切合作的研究经验。

This award funds the development of new techniques for applying atomic scale simulation to study the physics of nanoscale friction. These techniques aim to extend the time scales accessible with simulation, which are currently limited to less than a microsecond. This renders current methods unsuitable for simulating processes that take place at sliding rates considerably slower than 0.1 m/s. For comparison, AFM experiments and MEMs sliding take place at sliding speeds of 10-6 ? 10-9 m/s. These simulation methods will also be extended to inherently non-equilibrium simulations. It is anticipated that such long-time non-equilibrium simulations will be useful for testing theories of friction against simulations in which a single-asperity contact is realistically modeled.The goal of this project is to expand our knowledge regarding the fundamental physics and chemistry of friction on the nanoscale. Such knowledge is critical for the design of micro- and nano- electromechanical devices (MEMS/NEMS), interpreting the results of atomic force microscopy (AFM) for surface characterization and developing effective methods for lubrication in precision applications. Investigations will enable the analysis of transitions in frictional response with respect to sliding rate and temperature. These methods will also lay the groundwork for investigations into the effect of adsorbates such as hydrocarbons and the influence of surface chemistry on friction and wear and have the potential to be extended to a variety of other systems including studies of fracture, fatigue, adhesion and other non-equilibrium materials processes. The project will support a graduate student and postdoctoral researcher. The investigator will also coordinate with the outreach activities the JHU MRSEC and PREM grant activities to bring an underrepresented minority student into the lab each summer to gain research experience working closely with the PI and graduate student.