Structural and dynamical heterogeneities in two-dimensional melting

TL;DR

This study uses molecular dynamics to analyze structural and dynamical heterogeneities during two-dimensional melting, revealing intermediate hexatic states with enhanced fluctuations and specific relaxation dynamics.

Contribution

It provides detailed insights into the heterogeneities and relaxation behaviors in 2D melting, highlighting the properties of the hexatic phase with large-scale fluctuations.

Findings

Enhanced density fluctuations at small wave numbers in hexatic phase

Exponential relaxation of density scattering function with decay rate ~ k^{2.6}

Presence of intermediate hexatic states between crystal and liquid

Abstract

Using molecular dynamics simulation, we study structural and dynamical heterogeneities at melting in two-dimensional one-component systems with 36000 particles. Between crystal and liquid we find intermediate hexatic states, where the density fluctuations are enhanced at small wave number k as well as those of the six-fold orientational order parameter. Their structure factors both grow up to the smallest wave number equal to the inverse system length. The intermediate scattering function of the density S(k,t) is found to relax exponentially with decay rate Gamma_k ~ k^z with z~2.6 at small k in the hexatic phase.