Extended Time Scale Simulation Studies of Nanoscale Friction

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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.