泛函积分方法计算推广的Anderson模型的化学势

Study of the Chemical Potential of the Extended Anderson Model with the Functional Integral Approach

寻找能够越出平均场近似的理论方法是量子统计研究领域中的一个重要课题，泛函积分方法的研究提供了一种可行的超越平均场近似的重要途径．以推广的Ａｎｄｅｒｓｏｎ模型为出发点，利用泛函积分方法所得到的一阶谐波近似（ＦＨＡ），可以得到这一模型体系的化学势随载流子数密度的变化结果．化学势在一定的载流子密度下会出现非常明显的突变．关于化学势突变这一结果可以对最新的有关高温超导的理论计算结果进行修正，并且能够对高Ｔｃ超导体在这些点上掺杂效率的突变以及Ｔｃ与二维载流子相对浓度的普适关系进行解释．

Findeing the theory method beyond the mean field theory is an important question. The study of the functional integral approach (FIA) can provide a feasible approach beyond the mean field. The first harmonic approximation (FHA) of the functional integral approach (FIA) has been applied to the study of the chemical potential of a generalized Anderson model. The FHA is beyond the mean field theory. An interesting sudden change of the chemical potential was found at a certain carrier desity. The sudden change of the chemical potential can amend the latest numerical results about the high temperature superconductivity and explain the sudden change of doping efficiency at certain points and the universal relationship between T c and the hole concentration.