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用微扰展开的方法计算了单带扩展的 Hubbard 模型的磁化率。讨论了最近邻格点的电子与电子之间的排斥作用对系统铁磁和反铁磁磁化率的影响。并指出,在二阶近似的情况下该模型在高密度区存在反铁磁相变,相邻格点电子之间的相互排斥对反铁磁临界温度几乎没有影响。
The perturbation expansion method was used to calculate the susceptibility of the Hubbard model with a single extension. The effect of the repulsion between electrons and electrons at the nearest neighbor points on the ferromagnetic and antiferromagnetic susceptibility of the system is discussed. It is pointed out that in the case of the second-order approximation, there exists an anti-ferromagnetic phase transition in the high-density region, and the mutual exclusion of neighboring lattice electrons has almost no effect on the anti-ferromagnetic critical temperature.