AVS 58th Annual International Symposium and Exhibition
    Tribology Focus Topic Thursday Sessions
       Session TR+AS+SS-ThM

Paper TR+AS+SS-ThM12
Atomic Stick-Slip Friction Studied by Optimally-Matched Accelerated MD Simulations and AFM Experiments

Thursday, November 3, 2011, 11:40 am, Room 111

Session: Atomic-scale Characterization of Tribological Interfaces
Presenter: Yalin Dong, Purdue University
Authors: Y. Dong, Purdue University
Q. Li, University of Pennsylvania
R.W. Carpick, University of Pennsylvania
A. Martini, Purdue University
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Atomic-scale stick-slip friction of platinum on gold (111) surface is quantitatively studied both experimentally and through optimally-matched accelerated molecular dynamics (MD). In order to make a direct comparison between simulation and experiment, many other factors are matched as closely as possible, such as misalignment, size effect of the tip, cantilever compliance, normal load and so on. The Parallel Replica Dynamic Method (ParRep) is used to accelerate the simulation so scan velocities can be decreased to scales approaching those used in atomic force microscope experiments. A logarithm dependence of friction on scanning velocity is observed both in Atomic Force Microscope (AFM) and MD reveals that at low speed the atomic friction lies in thermal activation regime. A further comparison shows that AFM and MD provide consistent energetics, which supports that MD can be used to interpret AFM results; but attempt frequencies differ by orders of magnitude, which is attributed to the inertia discrepancy.