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利用突变理论的尖点突变模型对近晶液晶的ＳｍＡ－ＳｍＣ相变过程进行了研究。这个相变模型包含状态参数Ｐ；与液晶体系的盒厚和表面能相关的参数α；与温度和磁场相关的参数β。从Ｌａｎｄａｕ自由能系统的这三组参数出发，得到了两个稳定区和一个亚稳区的相空间。在这三维空间中不同的相变途径得到连续变化、弱连续变化或尖点突变式不连续变化，从而通过尖点突变模型可以预测近晶型液晶体系的状态变化。当磁场强度、盒厚和表面能取常值时，其结果与Ｃ．Ｃ．Ｈｕａｎｇ等人的研究结果一致。
The catastrophe theory cusp catastrophe model was used to study the SmA-SmC phase transition of smectic liquid crystal. This phase change model contains the state parameter P; the parameter α related to the cell thickness and surface energy of the liquid crystal system; and the parameter β related to the temperature and the magnetic field. Starting from the three sets of parameters of the Landau free energy system, the phase space of two stable regions and one metastable region is obtained. In this three-dimensional space, the different phase transition paths are continuously changed, weakly continuous or cusp catastrophically discontinuous, so the cusp catastrophe model can predict the state change of smectic liquid crystal system. When the magnetic field strength, box thickness and surface energy to take constant, the result with C. C. Huang et al.’s findings are consistent.