Nanowire Melting Modes during the Solid-Liquid Phase Transition: Theory and Molecular Dynamics Simulations

TL;DR

This paper combines theoretical modeling and molecular dynamics simulations to analyze nanowire melting mechanisms, revealing how wire length influences whether melting occurs via interface front movement or pinch-off instability.

Contribution

It introduces a perturbed capillary fluctuation model to predict melting modes and validates these predictions with molecular dynamics simulations, highlighting the role of wire length.

Findings

Longer nanowires tend to melt via pinch-off instability.

Shorter nanowires favor interface front movement towards the center.

Preferred instability modes scale with nanowire length.

Abstract

Molecular dynamics simulation have shown that after initial surface melting, nanowires can melt via two mechanisms: an interface front moves towards the wire centre; the growth of an instability at the interface can cause the solid to pinch-off and breakup. By perturbing a capillary fluctuation model describing the interface kinetics, we show when each mechanism is preferred and compare the results to molecular dynamics simulation. A Plateau-Rayleigh-type of instability is found, and suggests longer nanowires will melt via a instability mechanism, whereas in shorter nanowires the melting front will move closer to the centre before the solid pinch-off can initiate. Simulations support this theory; preferred modes that destabilise the interface are proportional to the wire length, with longer nanowires preferring to pinch-off and melt; shorter wires have a more stable interface close to their melting temperature, and prefer to melt via an interface front that moves towards the wire centre.