向列液晶表面弹性能K13项的物理效应及检验方法

通过解析推导和数值计算的方法，得到了平衡态指向矢满足的微分方程和边界条件.研究了表面弹性能K13项对磁场作用下的弱锚定向列液晶盒Fréedericksz转变性质的影响.结果表明，表面弹性能K13项的存在对液晶系统的自由能有很大的影响，从而改变转变的性质，诱导液晶盒在阈值点发生一级Fréedericksz转变.给出了发生一级转变的物理条件，它除了与液晶的结构和材料有关外，还依赖于液晶表面弹性能K13项，同时给出了由此判断K13项是否存在的检验方法. 关键词： 表面弹性能K13项 弱锚定 Fréedericksz转变

Physical effects caused by surface elastic term K13 on nematic-liquid-crystal cells and the detecting scheme about K13

Base on successful solution of the problems in judging whether the surface elastic term K13 of nematic liquid crystal exists or not, the equilibrium equation and boundary condition of the director have been obtained by the methods of analytical derivation and numerical calculation. The influence of the surface elastic energy term K13 on the properties of Fréedericksz transition of weak anchoring nematic liquid crystal cell under a magnetic field has been investigated in detail. The results show that the existence of K13 has influence on the free energy of the liquid crystal system so great as to change the property of the transition and induce a first-order Fréedericksz transition. The conditions for this transition are obtained. They depend on the surface elastic energy term K13 besides the structure and material of the system. The method of judging whether K13 term exists or not by Fréedericksz transition has been given.