Orientation Walls Induced By Inhomogeneous Surfaces In Nematic Liquid Crystal

Defects are ubiquitous in liquid crystals. Topological defects arises as a result ofbroken continuous symmetry. Commonly observed defects in condensed matter aredislocation and disclination. We investigated the defects caused by different boundaryconditions based on Landau-de Gennes theory.We make numerical simulation of the defects under different kinds of boundaries,using the relaxation method. Three kinds of boundary conditions are studied: the planeboundary, the single-step boundary and the double-step boundary. The second-order tensor,eigenvalues as well as the biaxial parameters of the system at equilibrium state werecalculated.The results show that there exists eigenvalue exchange across the defect core; thedefect centre is uniaxial surrounded by a strong biaxial region. The defect core will movesupward because of the inhomogeneous surfaces. The two defects interfere with each otherin the double-step boundary condition. The interference becomes stronger as the stepbecoming higher, or the gap between two steps becoming narrower.