SKM 2023 – scientific programme
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O: Fachverband Oberflächenphysik
O 4: Tribology: Surfaces and Nanostructures
O 4.6: Talk
Monday, March 27, 2023, 11:45–12:00, GER 37
Atomic friction over bonds: Impact of the chemical neighbourhood — •Lukas Hörmann1, Johannes J. Cartus1, Alfred J. Weymouth2, and Oliver T. Hofmann1 — 1Institute of Solid State Physics, Graz University of Technology, Graz, Austria — 2Universität Regensburg, Regensburg, Germany
Friction causes a significant amount of energy loss in any moving mechanical device. Given the trend toward the miniaturisation of devices, studies of the fundamental mechanisms governing friction at the atomic scale become ever more important. At this scale, friction is governed by electronic and phononic excitations as well as by the potential energy surface (PES) at the interface.
We computationally investigate these mechanisms on the example of a CO-tip of a lateral force microscope oscillating above a PTCDA monolayer on Cu(111). Our investigation combines ab-initio electronic structure methods with machine-learning algorithms to predict highly accurate PESs and to estimate frictional energy dissipation. We gauge the dependence of frictional energy dissipation on the local chemical environment, i.e. the location of the CO-tip above the surface during the friction measurement. Moreover, we investigate how the oscillation direction and the stiffness of the CO-tip affect friction. Hereby we study the role of quantum-mechanical interactions by comparing our results to friction estimates based on a Lennard-Jones potential as well as experimental measurements. Finally, we investigate frictional energy dissipation channels by studying how the movement of the CO-tip may be damped as a result of electronic friction.