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利用双轴向列相液晶表面能对指向矢和序参量矩阵的旋转不变性 ,构造了与指向矢 ^a ,^b ,^c对易取向轴 ^a0 ,^b0 ,^c0 的偏离有关的表面能Fs(a ,b ,c) ,以及与序参量矩阵有关的表面能Fs(Q) ,并得到两种表达式的等价形式 .在Fs(a ,b ,c)和Fs(Q)中分别有四个和两个独立参量 .为讨论上述独立参量的物理意义 ,假设一液晶分子对表面相互作用的简单模型 ,将液晶分子沿易取向轴 ^b0 ,^c0 的双轴性取向看成是受到沿 ^b0 ,^c0 两相互垂直的平均场作用的结果 .为测量表面锚泊系数 ,考虑了三种简单形变位型 ,即在外磁场中 ^b和 ^c绕 ^a0 ,^c和 ^a绕 ^b0 ,^a和^b绕 ^c0 的Freedericksz相变 .通过测量其Freedericksz相变的磁场阈值 ,可求出表面能中与这三个形变有关的锚泊系数Wa,Wb,Wc.
Using the surface invariance of biaxial nematic liquid crystal to the rotation invariance of the director and the order parameter matrix, we construct the relation between the deviation of easy orientation axes ^ a0, ^ b0, ^ c0 The surface energy Fs (a, b, c) and the surface energy Fs (Q) related to the order parameter matrix are obtained and the equivalent forms of the two expressions are obtained. In order to discuss the physical meaning of the above independent parameters, assuming a simple model of liquid crystal molecules on the surface interaction, the liquid crystal molecules along the easy axis ^ b0, ^ c0 biaxial orientation As a result of the average field interaction along the two b0, ^ c0 perpendicular to each other.For the measurement of surface anchoring coefficient, consider three simple deformation type, that is in the external magnetic field ^ b and ^ c around ^ a0, ^ c and ^ a around ^ b0, ^ a and ^ b around ^ c0 Freedericksz phase transition. By measuring the Freedericksz phase transition of the magnetic field threshold can be obtained in the surface energy of these three deformation-related anchor coefficient Wa, Wb, Wc.