The improved theory have succeeded in applying to gaussian model . in the third chapter , based on the single - spin transition dynamics , we discuss the time evolution of the local magnetization in the anisotropic three - dimensional xy model under the zero external field 第三章在单自旋跃迁临界动力学的基础上,讨论零场下三维( 3d )各向异性晶格上xy模型的局域磁化强度的时间演化。