A Peierls Perspective on Mechanisms of Atomic Friction

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The objective of this research is to develop a Peierls perspective on the atomic-friction mechanisms from the spatiotemporal evolution of interface defect structures. Despite a quantitative experimental capability of examining nanoscale frictional behavior, existing modeling efforts, such as Tomlinson-type models or molecular simulations, are still unable to quantitatively explain the effects of lattice incommensurability, rate- and temperature-dependence, etc. A Peierls-type framework will be established to replace singular defect model by the inhomogeneous slip field on the interface. Experimental observations, such as structural lubricity, frictional anisotropy, and contact size dependence, can be explained as a consequence of initiation and multiplication of interface dislocations and their interactions with pre-existing interface defects. From the kinetics standpoint, the proposed work will examine the spatially inhomogeneous nature of the rate-determining process, accurately calculate the activation energy with respect to the interface defects, and thus explain the thermally activated frictional behavior.The uniqueness of the proposed work, as compared to a vast literature in this field, is the ability to quantitatively predict the atomic processes that govern the spatiotemporal evolution of the interface defects during friction. This viewpoint enables quantitative experimental comparisons and resolves drawbacks and difficulties of existing modeling efforts. It will open a broad door for both undergraduate and graduate students to participate in a multi-disciplinary education/research environment, and thus advances and enhances focused research and education activities in the PI?s institute. The PI will develop new instructional materials and hands-on computational demonstrations for incorporation into a variety of outreach and diversity programs, and thus promote the interests of high school and college students in science and engineering careers, as well as the engagement of public awareness.