Characterization of Phase Transition in Heisenberg Fluids from Density Functional Theory

作     者：LI Liang-Sheng LI Li CHEN Xiao-Song 

作者机构：Institute of Theoretical Physics Chinese Academy of Sciences P.O. Box 2735 Beijing 100190 China 

出 版 物：《Communications in Theoretical Physics》 (理论物理通讯（英文版）)

年 卷 期：2009年第51卷第2期

页      面：287-292页

核心收录：

学科分类：081704[工学-应用化学] 0809[工学-电子科学与技术（可授工学、理学学位）] 07[理学] 070304[理学-物理化学(含∶化学物理)] 070205[理学-凝聚态物理] 08[工学] 0817[工学-化学工程与技术] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0703[理学-化学] 0702[理学-物理学] 

基　　金：supported by the National Natural Science Foundation of China under Grant No.10325418 

主　　题：critical phenomena order-disorder magnetic liquid 

摘      要：The phase transition of Heisenberg fluid has been investigated with the density functional theory in mean-field approximation （MF）. The matrix of the second derivatives of the grand canonical potential Ω with respect to the particle density fluctuations and the magnetization fluctuations has been investigated and diagonalized. The smallest eigenvalue being 0 signalizes the phase instability and the related eigenvector characterizes this phase transition. We find a Curie line where the order parameter is pure magnetization and a spinodal where the order parameter is a mixture of particle density and magnetization. Along the spinodal, the character of phase instability changes continuously from predominant condensation to predominant ferromagnetic phase transition with the decrease of total density. The spinodal meets the Curie line at the critical endpoint with the reduced density p＊=pσ3=0.224 and the reduced temperature T＊ =kT/ε=1.87 （σ is the diameter of Heisenberg hard sphere and e is the coupling constant）.