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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 14: Condensed-Matter Simulations augmented by Advanced Statistical Methodologies (joint session DY/CPP)

CPP 14.3: Vortrag

Freitag, 1. Oktober 2021, 10:30–10:45, H2

Noncontact friction: The role of viscous friction and its non-universality — •Miru Lee¹, Niklas Weber², Richard Vink², Cynthia Volkert², and Matthias Krüger¹ — ¹Institut für Theoretische Physik, Friedrich- Hund-Platz 1, 37077 Göttingen — ²Institut für Materialphysik, Friedrich-Hund-Platz 1, 37077 Göttingen

Obtaining theoretical predictions for friction during sliding motion is challenging due to the complex nature of the problem. In the so-called noncontact regime, the friction tensor is given by the leading order of the pairwise interactions between the probe and the surface atoms [1]. In such a regime, one can thus find an analytic expression of the friction tensor [2]. Starting from a stochastic viscoelastic solid model, we identify the two paradigmatic dissipation mechanisms [3]: phonon radiation, prevailing even in a purely elastic solid, and phonon damping, e.g., caused by viscous motion of crystal atoms. At small probe-surface separations, phonon damping dominates over phonon radiation, and vice versa at large separations. Phonon radiation is furthermore universal; there exists a general one-to-one mapping between the mean probe-surface force and the resulting friction. In contrast, phonon damping is non-universal, and no such general relation exists; it is subject to the details of the underlying pairwise interaction, e.g., the interaction range. For certain cases, the friction can even decrease with increasing surface area the probe interacts with.
[1] M. Lee, R. Vink, M. Krüger, Phys. Rev. B 101, 235426 (2020)
[2] A. I. Volokitin, et. al., Phys. Rev. B 73, 165423 (2006)
[3] M. Lee, R. Vink, C. Volkert, M. Krüger, In preparation.