Hubbard－Hirsch模型中的电子相关效应

ELECTRON CORRELATION EFFECT IN THE HUBBARDARD-HIRSCH MODEL

基于同一格点的电子相关，把局域方法用于Ｈｕｂｂａｒｄ－Ｈｉｒｓｃｈ模型铁磁相。在二阶计算中使用Ｒ＝０，ａ近似，仔细研究了电子相关效应对基态相图的影响．由于计及了密度矩阵非对角元，其影响与Ｒ＝０近似相比变弱。

Abstract Based on the single-site electron correlation, the local approach has been usedto investigate the ferromagnetic phase in the Hubbard-Hirsch model.Using theR=0,a approximation in second-order calculation,the electron Correlation effecton the phase diagram has been studied Carefully.Comparing with those of the R=0approximxation,the electron correlation effect becomes weaker due to taking intoaceount the nondiagonal elements of density matrix.