Investigate Into Several Structures In Hybird Nematic Liauid Crysyal Induce -1/2 Defect

Within the Landau-de Gennes theory,we have investigated the transition among four structures (i.e.,pure hybrid aligned nematic structure,symmetric distortions with a line defect structure,eigenvalue exchange structure and homeotropic structure) as the cell thickness d and surface anchoring varies.In the condition of unilateral weak anchoring boundary,the asymmetric boundary conditions repel the defect to the weak anchoring boundary.In both unilateral and bilateral weak anchoring boundary conditions,the line defect structure transforms into the eigenvalue exchange structure at a critical value dc,and the critical thicknesses dc of structure transitions become higher with anchoring strength increasing.Furthermore,the free energy calculation shows another critical thickness dth.For dc<d<dth,eigenvalue exchange structure is stable.For d>dth,line defect structure is stable,while for d<dc,eigenvalue exchange structure only exists.