Molecular dynamics simulations of reflection and adhesion behavior in Lennard-Jones cluster deposition

TL;DR

This study uses molecular dynamics simulations to explore how atomic clusters either adhere to or reflect from surfaces during collisions, revealing the critical role of the Weber number and collision regimes in determining outcomes.

Contribution

The paper introduces a detailed analysis of collision regimes and the transition between adhesion and reflection based on the Weber number, linking microscopic dynamics to macroscopic theories.

Findings

Transition between adhesion and reflection occurs at Weber number around unity.

Two collision regimes identified: elastic with small deformation, and inelastic with large deformation.

Adhesion probability can be bimodal depending on collision parameters.

Abstract

We conduct molecular dynamics simulations of the collision of atomic clusters with a weakly-attractive surface. We focus on an intermediate regime, between soft-landing and fragmentation, where the cluster undergoes deformation on impact but remains largely intact, and will either adhere to the surface (and possibly slide), or be reflected. We find that the outcome of the collision is determined by the Weber number, We i.e. the ratio of the kinetic energy to the adhesion energy, with a transition between adhesion and reflection occurring as We passes through unity. We also identify two distinct collision regimes: in one regime the collision is largely elastic and deformation of the cluster is relatively small but in the second regime the deformation is large and the adhesion energy starts to depend on the kinetic energy. If the transition between these two regimes occurs at a similar kinetic energy to that of the transition between reflection and adhesion, then we find that the probability of adhesion for a cluster can be bimodal. In addition we investigate the effects of the angle of incidence on adhesion and reflection. Finally we compare our findings both with recent experimental results and with macroscopic theories of particle collisions.