Crystal nucleation of colloidal hard dumbbells

TL;DR

This study uses computer simulations to analyze how colloidal hard dumbbells nucleate crystals, examining the effects of aspect ratio and phase structure, and comparing nucleation rates with spontaneous events.

Contribution

It introduces a comprehensive simulation approach to quantify nucleation barriers and rates for different crystal phases in colloidal dumbbells, including structural insights.

Findings

Good agreement between calculated and observed nucleation rates.

Aspect ratio influences nucleation of different crystal phases.

High free energy barriers suppress CP1 crystal nucleation.

Abstract

Using computer simulations we investigate the homogeneous crystal nucleation in suspensions of colloidal hard dumbbells. The free energy barriers are determined by Monte Carlo simulations using the umbrella sampling technique. We calculate the nucleation rates for the plastic crystal and the aperiodic crystal phase using the kinetic prefactor as determined from event driven molecular dynamics simulations. We find good agreement with the nucleation rates determined from spontaneous nucleation events observed in event driven molecular dynamics simulations within error bars of one order of magnitude. We study the effect of aspect ratio of the dumbbells on the nucleation of plastic and aperiodic crystal phases and we also determine the structure of the critical nuclei. Moreover, we find that the nucleation of the aligned CP1 crystal phase is strongly suppressed by a high free energy barrier at low supersaturations and slow dynamics at high supersaturations.