双轴性向列相液晶的相变理论

Phase transition in biaxial nematic liquid crystal

假设一双轴性向列相液晶分子简单相互作用模型 ,利用平均场理论 ,得到从各向同性相至单轴向列相、单轴向列相至双轴向列相的相变 .结果表明 ,在一定温度范围内 ,分子形状的非轴对称性可导致系统双轴向列相的产生 .在核磁共振实验中 ,导出双轴向列相序参数与谱线分裂频率间的一般关系 ,并讨论序参数测量性的可能性 .

Assuming a simple biaxial molecular interaction model in nematic liquid crystal, and using the mean field approximation, phase transitions from isotropic to uniaxial nematics, uniaxial to biaxial nematics are obtained. The result obtained shows that at certain temperatures, the biaxial phases are induced by the asymmetry of molecular shape of liquid crystal. In nuclear magnetic resonance experiment, a general relation between order parameters and spectrum frequency splitting is derived, and possible experimental measurement is discussed.