Crystal growth from a supersaturated melt: relaxation of the solid-liquid dynamic stiffness

TL;DR

This study models crystal growth from a supersaturated melt using molecular dynamics, revealing rapid convergence of interface properties and the applicability of capillary wave theory to dynamic stiffness during growth.

Contribution

It demonstrates that off-equilibrium dynamic stiffness can be extracted during rapid growth and that it converges quickly to equilibrium values, advancing understanding of solid-liquid interface dynamics.

Findings

Growth speed peaks above solid coexistence density

Interface properties rapidly reach equilibrium-like behavior

Dynamic stiffness converges to equilibrium stiffness faster than diffusion times

Abstract

We discuss the growth process of a crystalline phase out of a metastable over-compressed liquid that is brought into contact with a crystalline substrate. The process is modeled by means of molecular dynamics. The particles interact via the Lennard-Jones potential and their motion is locally thermalized by Langevin dynamics. We characterize the relaxation process of the solid-liquid interface, showing that the growth speed is maximal for liquid densities above the solid coexistence density, and that the structural properties of the interface rapidly converge to equilibrium-like properties. In particular, we show that the off-equilibrium dynamic stiffness can be extracted using capillary wave theory arguments, even if the growth front moves fast compared to the typical diffusion time of the compressed liquid, and that the dynamic stiffness converges to the equilibrium stiffness in times much shorter than the diffusion time.