向列相液晶薄层的有限尺寸效应和相变

Effect of Finite Sizes and Phase Transition in Nematic Liquid Crystal Film

在分子场近似下研究 个分子层构成的向列相液晶薄层.使用文献上最近提出的空间各向异性两体作用势.存在两个模型,分别给出液晶弹性常数到势参数的两种映射方案.对液晶PAA 进行了数值计算.模型 I 给出液晶指向矢垂直薄层表面排列,而模型 II 给出指向矢平行于薄层表面排列.两个模型给出有限尺寸效应对向列相-各向同性相相变温度的影响也不同.

Nematic liquid crystal film composed of molecular layers is studied by means of themolecular field ap- proximation. Spatially anisotropic pair potential appeared recently in literature is used. We investigate two models, which give two mapping schemes from the elastic constants of liquid crystal to the potential parameters, respectively. Numerical calculations are made for liquid crystal para-azoxyanisole (PAA). The director of liquid crystal is vertical to the surface of the film from the viewpoint of model I, but it is parallel to the surface from model II. The effects of finite sizes on the nematic-isotropic phase transition temperature are also different for two models.