Structure and dynamics of interfaces between two coexisting liquid crystalline phases

TL;DR

This paper uses the phase-field-crystal model to study the structure and thermodynamics of interfaces between coexisting liquid crystalline phases, revealing detailed profiles and dynamics of order parameters in two dimensions.

Contribution

It provides the first numerical analysis of interfacial profiles and dynamics between various liquid crystalline phases using the phase-field-crystal model.

Findings

The nematic order interface is wider than the density interface.

Density decreases before the nematic order increases approaching the interface.

Profiles of order parameters can shift by more than a lattice constant.

Abstract

The phase-field-crystal model is used to access the structure and thermodynamics of interfaces between two coexisting liquid crystalline phases in two spatial dimensions. Depending on the model parameters there is a variety of possible coexistences between two liquid crystalline phases including a plastic triangular crystal (PTC). Here, we calculate numerically the profiles for the mean density and the nematic order tensor across the interface for isotropic-PTC and columnar-PTC respectively smectic A-PTC coexistence. As a general finding, the width of the interface with respect to the nematic order parameter characterizing the orientational order is larger than the width of the mean density interface. In approaching the interface from the PTC side, at first the mean density goes down and then the nematic order parameter follows. The relative shift of the two profiles can be larger than a full lattice constant of the plastic crystal. Finally, we also present numerical results for the dynamic relaxation of an initial order-parameter profile towards its equilibrium interfacial profile. Our predictions for the interfacial profiles can in principle be verified in real-space experiments of colloidal dispersions.