材料期刊网

在扭曲向列相中，基于Landau-deGennes理论，利用二维松弛迭代方法，研究了s＝±1/2扭曲向错的有序重构，给出了随着盒厚减小缺陷核的双轴结构。在临界值dc?≈9ξ(ξ是序参数变化的相干长度)，有序重构结构是稳定态，而带缺陷结构是亚稳态，此时系统缺陷结构和双轴性开始沿基板方向扩散。相对于没有初始向错的情况，本征值交换为稳定解对应的盒厚较大。在临界盒厚dc≈7ξ，系统发生双轴性转变，双轴性结构扩散到整个液晶盒，形成双轴壁。在盒厚d≈9ξ时力达到极大值，而d≈7ξ时力达到极小值。对于非对称弱锚泊边界条件，随着锚泊强度的降低，弱锚泊边界将向错逐渐驱出边界。

Within the Landau-de Gennes theory,the order reconstruction of s =±1/2 twist disclina-tions in a twisted nematic cell is investigated,using the two-dimensional relaxation iterative method. The biaxial structure of the defect core as the cell gap decreasing is explored.At a critical value of d c ?≈ 9ξ (hereξ is the characteristic length for order-parameter changes),the exchange solution is sta-ble,while the defect core solution becomes metastable,where the system starts to stretch the defect structure and the biaxiality starts to propagate inside of the cell.Comparing to the case with no initial disclination,the value at which the exchange solution becomes stable increases relatively.At a critical separation of d c ≈ 7ξ,the system undergoes a biaxial transition,and the defect core merges into a bi-axial wall with large biaxiality.The force reaches a maximum at d ≈ 9ξ,and a local minimum at d ≈7ξ.For weak anchoring boundary conditions,because of the weakened frustration,the asymmetric boundary conditions repel the defect to the weak anchoring boundary as the anchoring strength coeffi-cient decreasing.