【摘要】 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。更多还原

【Abstract】 The magnetic susceptibility of the extended Hubbard model with single bandis calculated using perturbation-expansion method. A discussion is made aboutthe influence of repulsion between electrons at neighbor sites on the ferro-magnetic/antiferromagnetic susceptibility. It is found that under second appro-ximation there exists an antiferromagnetic phase transf ormation of the modelin the region of high electron density. Moreover, there will sarcely, be anyinfluence of the mutual repulsion beween eletrons at neighbor sites on theantiferromagnetic critical temperature.更多还原