用临界点附近的涨落讨论Landau相变理论适用范围

The Discussion for Applicable Scope of Landau Theory of Phase Transition in Flunction of the Critical Point Nearby

Landau相变理论是研究晶体各种结构相变的有力工具.在临界点附近某些序参量的涨落很大,导致Landau相变理论失去作用.在自由能密度的展开式中需要考虑Ginzburg梯度项,通过对相对几率和关联函数的傅里叶分量来分析临界点附近的序参量的涨落,并由此得出Landau相变理论的适用范围.

The Landau theory of phase transition is a powerful tool which studies all kinds of structural phase transition of crystal. In the critical point nearby, some order parameters fluctuate heavily and it causes that the Landau theory of phase transition has not work. It needs to consider the Ginzburg gradient item in flee energy density expansion. By dint of the relative probability and the Fourier component of connection function, we analyse the fluctuation of the order parameters in the critical point nearby, and thus we obtain the applicable scope of the Landau theory of phase transition.