Molecular dynamics study of dynamical contact between a nanoscale tip and substrate for atomic force microscopy experiments

H Kim and G Venturini and A Strachan, JOURNAL OF APPLIED PHYSICS, 112, 094325 (2012).

DOI: 10.1063/1.4762016

We propose a molecular dynamics approach to model the dynamical interaction of a nanoscale tip with a substrate under conditions relevant to dynamic atomic force microscopy (AFM). We apply this approach to a half-sphere platinum tip contacting a flat surface of the same metal and study how the input dynamical variables (loading rate during contact and nominal separation between the tip and the substrate) affect the observed interaction between the tip and the substrate. We predict the energy dissipated per cycle and study the use of force- displacement curves to extract local stiffness. We find that, when using nanoscale probes, accurate values can only be obtained for a narrow range of indentations, large enough for continuum elasticity to apply and small enough to avoid plastic deformation. Simulations using the proposed approach are expected to be useful to explore operating conditions of AFM and interpret their results. (C) 2012 American Institute of Physics.

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