液晶SmC*相自发极化的统计理论

采用格胞模型，定义在格胞中心上的极化序参量．选用双轴性并具有横向电矩的分子作用势，求得系统的自由能，得到自发极化强度的大小和螺旋变化螺距的表达式．计算了DOBAMBC和3M2CPOOB等4种典型SmC^*相液晶的自发极化强度大小和螺距随温度的变化及其受分子横向电矩的影响，结果与实验相符．表明SmC^*相的自发极化强度主要产生于分子的双轴性和横向电矩． 关键词：

STATISTICAL THEORY OF SPONTANEOUS POLARIZATION IN SmC* LIQUID CRYSTALS

With cell model,the polarized order parameter is defined on cell center.By choice of interaction potential of biaxial molecules possessing a permanent electris dipole moment transverse to molecular axes,the system free energy is obtained.The approximate formula of spontaneous polarization and pitch is derived by calculation of variation to the free energy.We have calculated the temperature and the molecular transverse electric dipole dependence of the spontaneous polarization and pitch for four classic SmC^* liquid crystals of DOBAMBC and 3M2CPOOB etc.The calculations agree satisfactorily with experimental results.It is shown that the spontaneous polarization is mainly due to the molecular biaxiality and transverse electric dipole of the SmC^* liquid crystals.