Simulation of cohesive head-on collisions of thermally activated nanoclusters

TL;DR

This paper uses molecular dynamics simulations to study head-on collisions of thermally activated nanoclusters, revealing complex behaviors including a peak in restitution coefficient and anomalous rebounds exceeding unity.

Contribution

It introduces a detailed simulation study of nanocluster collisions considering thermal effects and identifies new phenomena not fully explained by existing theories.

Findings

Restitution coefficient peaks at certain impact speeds.

Existence of anomalous rebounds with coefficients greater than one.

Phase diagrams explaining rebound behaviors.

Abstract

Impact phenomena of nanoclusters subject to thermal fluctuations are numerically investigated. From the molecular dynamics simulation for colliding two identical clusters, it is found that the restitution coefficient for head-on collisions has a peak at a colliding speed due to the competition between the cohesive interaction and the repulsive interaction of colliding clusters. Some aspects of the collisions can be understood by the theory by Brilliantov {\it et al.} (Phys. Rev. E {\bf 76}, 051302 (2007)), but many new aspects are found from the simulation. In particular, we find that there are some anomalous rebounds in which the restitution coefficient is larger than unity. The phase diagrams of rebound processes against impact speed and the cohesive parameter can be understood by a simple phenomenology.