Disordered system with n orbitals per site: n= [] limit
Disordered system with n orbitals per site: n= [] limit
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每个位点有 n 个轨道的无序系统：n= [] limit
DOI：
10.1103/physrevb.19.783
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发表时间：
1979
影响因子：
3.7
通讯作者：
F. Wegner
中科院分区：
文献类型：
--
作者：
F. Wegner
介绍了一个d维晶格上每个位置都有n个电子态的随机无序系统的模型。它是Wigner把一个模型推广到d维，并把通常考虑的无序系统模型推广到每个格点的n个态。在弱散射体密集系统的极限n=∞范围内，可以精确地计算单粒子和双粒子格林函数。如果费米能量在带内，则本征态被扩展，剩余电导率是有限的。我们考虑了两种更特殊的情况：(I)在仅仅是位置-对角无序的情况下，n=∞解符合位置-对角元素的半圆分布的n=1相干势近似.(Ii)在“局部规范不变模型”中，当不同位置的位相完全不相关时，格林函数消失，除非这些点在局部空间中成对重合.除了规范不变模型的一种特殊情况外，系统(I)和(II)在L长度上的本征态之间表现出相同的长程关联，当能量差ω为零时，这种关联发散类似于|L1 1 2。
A model of a randomly disordered system with n electronic states at each site of a d-dimensional lattice is introduced. It is a generalization of a model by Wigner to d dimensions and an extension of the usually considered model for disordered systems to n states per site. In the limit n=∞, which is the limit of a dense system of weak scatterers, the one-and two-particle Green's function can be calculated exactly. The eigenstates are extended and the residual conductivity is finite, provided the Fermi energy is inside the band. Two special cases are considered more closely:(i) In the case of mere site-diagonal disorder the n=∞ solution agrees with the n= 1 coherent-potential approximation for a semicircle distribution of the site-diagonal elements.(ii) In a" local gauge invariant model," where the phases at different sites are completely uncorrelated, the Green's functions vanish unless the points coincide pairwise in local space. Except for a special case of the gauge-invariant model, the systems (i) and (ii) show the same long-range correlation between eigenstates over a length L which diverges like| ω|− 1 2 as the energy difference ω vanishes.