Theoretical evidence for a dense fluid precursor to crystallization

TL;DR

This paper uses density functional theory to show that fluids tend to crystallize via a dense fluid precursor, supporting the Ostwald rule of stages, contrasting with classical models of simultaneous densification and ordering.

Contribution

It provides theoretical evidence that crystallization proceeds through a metastable dense fluid state, challenging traditional views of direct ordering and densification.

Findings

Crystallization involves a metastable dense fluid state.

Supports Ostwald rule of stages in crystallization.

Contrasts with classical densification and ordering models.

Abstract

We present classical density functional theory calculations of the free energy landscape for fluids below their triple point as a function of density and crystallinity. We find that for both a model globular protein and for a simple atomic fluid modeled with a Lennard-Jones interaction, it is free-energetically easier to crystallize by passing through a metastable dense fluid in accord with the Ostwald rule of stages but in contrast to the alternative of ordering and densifying at once as assumed in the classical picture of crystallization.