Kinetic crystallisation instability in liquids with short-ranged attractions

ABSTRACT

Liquids in systems with spherically symmetric interactions are not thermodynamically stable when the range of the attraction is reduced sufficiently. However, these metastable liquids have lifetimes long enough that they are readily observable prior to crystallisation. Here we investigate the fate of liquids when the interaction range is reduced dramatically. Under these conditions, we propose that the liquid becomes kinetically unstable, i.e. its properties are non-stationary on the timescale of structural relaxation. Using molecular dynamics simulations, we find that in the square well model with range 6% of the diameter, the liquid crystallises within the timescale of structural relaxation for state points except those so close to criticality that the lengthscale of density fluctuations couples to the length of the simulation box size for typical system sizes. Even very close to criticality, the liquid exhibits significant structural change on the timescale of relaxation.

GRAPHICAL ABSTRACT

Keywords:

• Crystallisation
• liquid structure
• simple liquids

Acknowledgments

It is a pleasure to dedicate this paper to Daan Frenkel, the author would like to thank him for many inspiring discussions over the years. Zhaleh Ghaemi is gratefully acknowledged for her kind help with some of the preliminary simulations. We would like to thank John Russo and Nigel Wilding for stimulating discussions. Bob Evans is acknowledged for a most critical reading of earlier versions of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Funding

CPR gratefully acknowledges the Royal Society, European Research Council [ERC Consolidator Grant NANOPRS, project number 617266] and Kyoto University SPIRITS fund for financial support. This work was carried out using the facilities of the Advanced Computing Research Centre, University of Bristol.