Electronic versus phononic friction of xenon on silver

Abstract

Molecular dynamics simulations of a Xe monolayer sliding on Ag(001) and Ag(111) are carried out in order to ascertain the microscopic origin of friction. For several values of the electronic contribution to the friction of individual Xe atoms, the intra-overlayer phonon dissipation is calculated as a function of the corrugation amplitude of the substrate potential, which is a pertinent parameter to consider. Within the accuracy of the numerical results and the uncertainty with which the values of the relevant parameters are known at present, we conclude that electronic and phononic dissipation channels are of similar importance. While phonon friction gives rise to the rapid variation with coverage, the electronic friction provides a roughly coverage-independent contribution to the overall sliding friction.

Nanoscale sliding friction versus commensuration ratio: Molecular dynamics simulations

“…Given the theoretical arguments presented by Smith et al 2 and the numerical evidence also presented by them and by Liebsch et al 5 supporting the quadratic dependence of the friction coefficient with substrate corrugation, we fitted the data of Fig. 4 with the following expression:…”

“…Persson and Nitzan 3 found that the phononic friction was not significant in comparison with the electronic contribution, while Tomassone et al 4 found the opposite. On the other hand Liebsch et al 5 concluded that both contributions are important, but that the phononic friction strongly depends on the substrate corrugation amplitude. The abrupt change in the sliding friction at the superconductor transition observed by Dayo et al 9 provides additional support to the latter argument, showing that the electronic friction is of the same order of magnitude as the phononic one.…”

“…[2][3][4][5] Subsequently, a huge body of new and fascinating experiments on nanoscale friction has seen the light during the last 15 years. However, the theoretical interpretation of nanoscopic sliding experiments has evidenced some degree of disagreement, mainly related to incompatible results between different simulations, [3][4][5] in spite of the fact that they were performed for the same system with similar models and techniques. With the aim of finding some plausible explanation for these discrepancies we set out to study the relation between the topology and sliding friction coefficient .…”

“…6,7 Issues like how the energy dissipates on the substrate, which is the main dissipation channel ͑electronic or phononic͒, and how the phononic sliding friction coefficient depends on the corrugation amplitude were addressed, and partially solved, by several groups. [2][3][4][5] Yet in the specific case of Xe over Ag, three different groups tried either to explain or to estimate theoretically the experimental observations of Daily and Krim. 8 Despite the fact that they used similar models and similar simulation techniques to calculate the phononic contribution to friction, they got quite different results.…”

Nonlinear friction of a damped dimer sliding on a periodic substrate

“…2 Microscopic experiments on friction, 3 and subsequent theory and simulation were started only in the last 15 years. [4][5][6][7] Of the work that remains to be done to achieve a coherent picture of this complex phenomenon, an important aspect concerns nonlinear sliding friction. In his seminal paper, 8 Persson presented numerical simulations in the nonlinear regime of an adsorbate sliding over a periodic potential.…”