界面锚定能和扭曲向列液晶盒

Anchoring Energy of Interface and Twisted NLC Cell

向列液晶界面锚定能被认为是液晶分子与固体界面上分子相互作用势之和,据此导出了锚定能的新公式,它包含两项,因而有两个强度参量,其中第二项是由于界面诱导双轴性而引起的,倾角锚定强度Aθ和方位角锚定强度定Aφ的差别可归因于此。用新的锚定能公式详细研究了弱锚定扭曲(超扭曲)向列液晶盒,假定Aθ/Aφ=k11/k12,计算了阈值场强和饱和场强的大小,与以前我们认为的Aθ/Aφ=1情况做了比较。结果表明,倾角锚定强度Aθ与方位角锚定强度Aφ的关系对扭曲(超扭曲)向列液晶盒的阈值场强和饱和场强都有影响。

The anchoring energy of NLC is considered as the sum of the interfacial potential between the molecules of liquid crystal and the substrate surface molecules, on basis of which we deduce the new formula for anchoring energy of NLC. It includes two terms, so there are two anchoring strength. The second term is resulted from the biaxial property of the interface, and the difference between the tilt angle anchoring with the azimuthal angle anchoring can be contributed to the biaxial property of the interface. The theoretical explain of the new formula is given by a simple model. Adopting the new formula for anchoring energy and supposing A_θ/A_φ=k_(11)/k_(22), we investigate the weak anchoring twisted NLC cell by analytical method, calculate the threshold field and the saturation field, and the result is compared with that in the case of A_θ/A_φ=1. The results indicate that the relationship of the tilt angle anchoring energy and the azimuthal anchoring angle influences the threshold field and saturation field for the weaker anchoring twisted (super-twist ) NLC cell.