Influence of substrate potential shape on the dynamics of a sliding lubricant chain

TL;DR

This study explores how the shape of substrate potentials influences the frictional sliding behavior of an incommensurate lubricant chain, revealing significant effects on velocity quantization phenomena crucial for understanding nanoscale friction.

Contribution

It demonstrates that the shape parameter of the substrate potential critically affects the existence and stability of velocity quantization in sliding chains.

Findings

Shape variations significantly alter velocity plateaus.

Velocity quantization robustness depends on substrate potential shape.

Substrate shape influences the dynamics of incommensurate chains.

Abstract

We investigate the frictional sliding of an incommensurate chain of interacting particles confined in between two nonlinear on-site substrate potential profiles in relative motion. We focus here on the class of Remoissenet-Peyrard parametrized potentials $V_{\rm RP}(x,s)$, whose shape can be varied continuously as a function of $s$, recovering the sine-Gordon potential as particular case. The observed frictional dynamics of the system, crucially dependent on the mutual ratios of the three periodicities in the sandwich geometry, turns out to be significantly influenced also by the shape of the substrate potential. Specifically, variations of the shape parameter $s$ affects significantly and not trivially the existence and robustness of the recently reported velocity quantization phenomena [Vanossi {\it et al.}, Phys. Rev. Lett. 97, 056101 (2006)], where the chain center-of-mass velocity to the externally imposed relative velocity of the sliders stays pinned to exact "plateau" values for wide ranges of the dynamical parameters.