Liquid crystalline growth within a phase-field crystal model

TL;DR

This paper uses a phase-field crystal model to simulate liquid-crystal growth, focusing on crystal shape and defect formation, revealing how growth dynamics and initial phases influence morphology and topological defects.

Contribution

It introduces a novel PFC model simulation of liquid-crystal growth, analyzing shape variations and defect dynamics in different initial phases.

Findings

Shape of PTC in isotropic phase matches classical PFC predictions.

Shape of PTC in CSA phase depends on stripe orientation, producing irregular shapes.

Topological defects evolve from disclination pairs to vortex structures during growth.

Abstract

By using a phase-field crystal (PFC) model, the liquid-crystal growth of the plastic triangular phase is simulated with emphasis on crystal shape and topological defect formation. The equilibrium shape of a plastic triangular crystal (PTC) grown from a isotropic phase is compared with that grown from a columnar/smectic A (CSA) phase. While the shape of a PTC nucleus in the isotropic phase is almost identical to that of a classical PFC model, the shape of a PTC nucleus in CSA is affected by the orientation of stripes in the CSA phase, and irregular hexagonal, elliptical, octagonal, and rectangular shapes are obtained. Concerning the dynamics of the growth process we analyse the topological structure of the nematic-order, which starts from nucleation of $+\frac{1}{2}$ and $-\frac{1}{2}$ disclination pairs at the PTC growth front and evolves into hexagonal cells consisting of $+1$ vortices surrounded by six satellite $-\frac{1}{2}$ disclinations. It is found that the orientational and the positional order do not evolve simultaneously, the orientational order evolves behind the positional order, leading to a large transition zone, which can span over several lattice spacings.