Theoretical investigation of the anticorrugation effects on the tribological properties of the Xe/Cu interface

We present a molecular dynamics study of the slip time and static friction for a slab of Xe deposited on a slab of Cu. To put in evidence the role played by the phonon field of the two blocks, we compare results obtained with a substrate formed by fixed atoms with one formed by mobile atoms. In the last case the scattering between Xe and Cu mobile atoms is inelastic and there is an exchange of momentum and energy between the two blocks which produces disorder in the interface plane. This disorder favors a decrease of the static friction and a consequent increase of the slip time. We describe the interaction between Xe and Cu with a phenomenological multi-ion potential which gives rise to an anticorrugation of the charge distribution and reproduces very well the ab initio density functional calculations. Our model potential is a linear superposition of a corrugating potential and an anticorrugating one. For this reason we can study the static friction by passing from an anticorrugated to a fully corrugated system. We also investigate the slip time and we compare our results with recent experimental data measured with the quartz crystal microbalance technique.