Dislocation lines as the precursor of the melting of crystalline solids observed in Monte Carlo simulations

TL;DR

This study uses Monte Carlo simulations to reveal that dislocation lines form before melting in crystalline solids, serving as microscopic precursors to the phase transition.

Contribution

It demonstrates that dislocation lines are the key defect structures initiating melting, providing microscopic insight into the melting process in Lennard-Jones fcc crystals.

Findings

Dislocation lines appear at about 0.8 of melting temperature.

Long defect lines cross the entire system near melting.

Dislocation lines are identified as the melting precursors.

Abstract

The microscopic mechanism of the melting of a crystal is analyzed by the constant pressure Monte Carlo simulation of a Lennard-Jones fcc system. Beyond a temperature of the order of 0.8 of the melting temperature, we found that the relevant excitations are lines of defects. Each of these lines has the structure of a random walk of various lengths on an fcc defect lattice. We identify these lines with the dislocation ones proposed in recent phenomenological theories of melting. Near melting we find the appearance of long lines that cross the whole system. We suggest that these long lines are the precursor of the melting process.