Mean-field model of melting in superheated crystals based on a single experimentally measurable order parameter

Nikita P Kryuchkov,Stanislav O Yurchenko,Andrei V Sapelkin,Pavel V Ovcharov,Yilong Han,Wei Li,Nikita A Dmitryuk

doi:10.1038/s41598-021-97124-7

Abstract

Melting is one of the most studied phase transitions important for atomic, molecular, colloidal, and protein systems. However, there is currently no microscopic experimentally accessible criteria that can be used to reliably track a system evolution across the transition, while providing insights into melting nucleation and melting front evolution. To address this, we developed a theoretical mean-field framework with the normalised mean-square displacement between particles in neighbouring Voronoi cells serving as the local order parameter, measurable experimentally. We tested the framework in a number of colloidal and in silico particle-resolved experiments against systems with significantly different (Brownian and Newtonian) dynamic regimes and found that it provides excellent description of system evolution across melting point. This new approach suggests a broad scope for application in diverse areas of science from materials through to biology and beyond. Consequently, the results of this work provide a new guidance for nucleation theory of melting and are of broad interest in condensed matter, chemical physics, physical chemistry, materials science, and soft matter.

Highlights

Melting is one of the most studied phase transitions important for atomic, molecular, colloidal, and protein systems
Several questions that arise from the particle-resolved studies must be addressed: Could such a model be based on microscopic parameters experimentally accessible in real systems? Could these phenomena be described in the same manner in systems with different dynamic regimes (e.g. Brownian in globular proteins and colloids and Newtonian in dusty plasma and atomic systems)? How far the physical analogy between nonequilibrium phenomena in weakly damped and overdamped systems extends to melting in real atomic systems?
The white points are particles, the Voronoi cells are shown with solid grey lines, the cells are coloured in accordance to 2-value—the normalised mean-square displacement between particles in neighboring Voronoi cells[50]

Summary

Introduction

Melting is one of the most studied phase transitions important for atomic, molecular, colloidal, and protein systems. We tested the framework in a number of colloidal and in silico particle-resolved experiments against systems with significantly different (Brownian and Newtonian) dynamic regimes and found that it provides excellent description of system evolution across melting point. This new approach suggests a broad scope for application in diverse areas of science from materials through to biology and beyond. Single particle-resolved studies with colloids have allowed to investigate a wide In this context, a general theoretical framework that can link model systems and real materials with particleresolved (e.g. MD) simulations would be of significant practical interest. Several questions that arise from the particle-resolved studies must be addressed: Could such a model be based on microscopic parameters experimentally accessible in real (i.e. atomic and molecular) systems? Could these phenomena be described in the same manner in systems with different dynamic regimes (e.g. Brownian in globular proteins and colloids and Newtonian in dusty plasma and atomic systems)? How far (if at all) the physical analogy between nonequilibrium phenomena in weakly damped (complex plasmas) and overdamped (colloids, proteins) systems extends to melting in real atomic systems?

Methods

Results

Conclusion