Macroscopic nucleation phenomena in continuum media with long-range interactions

TL;DR

This paper demonstrates that in systems with long-range elastic interactions, nucleation can occur on a macroscopic scale, with the critical nucleus size proportional to the entire system, challenging traditional microscopic views.

Contribution

It introduces the concept of macroscopic barrier-crossing nucleation driven by elastic distortions, supported by molecular dynamics simulations of a spin-crossover model.

Findings

Nucleation size scales with system size in the presence of long-range interactions.

Elastic distortions enable macroscopic nucleation phenomena.

Simulation results confirm the theoretical prediction of macroscopic nucleation.

Abstract

Nucleation, commonly associated with discontinuous transformations between metastable and stable phases, is crucial in fields as diverse as atmospheric science and nanoscale electronics. Traditionally, it is considered a microscopic process (at most nano-meter), implying the formation of a microscopic nucleus of the stable phase. Here we show for the first time, that considering long-range interactions mediated by elastic distortions, nucleation can be a macroscopic process, with the size of the critical nucleus proportional to the total system size. This provides a new concept of "macroscopic barrier-crossing nucleation". We demonstrate the effect in molecular dynamics simulations of a model spin-crossover system with two molecular states of different sizes, causing elastic distortions.