Size-dependent commensurability and its possible role in determining the frictional behavior of adsorbed systems

TL;DR

This study uses molecular dynamics simulations to explore how size-dependent commensurability influences the frictional behavior of xenon adsorbed on different substrates, revealing critical factors affecting slip onset and friction.

Contribution

It introduces a detailed analysis of size-dependent commensurability effects on nanofriction, linking lattice misfit and coverage to frictional behavior in adsorbed systems.

Findings

Size-dependent island commensurability explains slip onset.

Lattice misfit impacts frictional differences between substrates.

Coverage and temperature influence interfacial structure and friction.

Abstract

Recent nanofriction experiments of xenon on graphene revealed that the slip onset can be induced by increasing the adsorbate coverage above a critical value, which depends on temperature. Moreover, the xenon slippage on gold is much higher than on graphene in spite of the same physical nature of the interactions. To shed light on these intriguing results we have performed molecular dynamics simulations relying on ab initio derived potentials. By monitoring the interfacial structure factor as a function of coverage and temperature, we show that the key mechanism to interpret the observed frictional phenomena is the size-dependence of the island commensurability. The latter quantity is deeply affected also by the lattice misfit, which explains the different frictional behavior of Xe on graphene and gold.