Perturbation expansion for the two-dimensional Hubbard model
Perturbation expansion for the two-dimensional Hubbard model
复制标题
二维哈伯德模型的微扰展开
DOI：
10.1103/physrevb.63.035104
复制
发表时间：
2000
影响因子：
3.7
通讯作者：
P. Schotte
中科院分区：
文献类型：
--
作者：
V. Zlatić;B. Horvatić;B. Dolički;S. Grabowski;P. Schotte
本文发展了一种计算时空表象中空穴掺杂二维Hubbard模型自能三阶修正的有效方法。使用戴森方程，我们评估的重整化谱函数在布里渊区的各个部分，并找到显着的修改相对于二阶理论，即使是相当小的值的耦合常数U。对于$ U \simeq W $，谱函数变得非物理的，其中W是导带的半宽度。当U<W时，在费米面附近，单粒子谱权在费米能附近的有限能量区间内减小。U的增加在谱函数的被占用部分和未被占用部分之间打开了间隙。
We develop an efficient method to calculate the third-order corrections to the self-energy of the hole-doped two-dimensional Hubbard model in space-time representation. Using the Dyson equation we evaluate the renormalized spectral function in various parts of the Brillouin zone and find significant modifications with respect to the second-order theory even for rather small values of the coupling constant U. The spectral function becomes unphysical for $ U \simeq W $, where W is the half-width of the conduction band. Close to the Fermi surface and for U<W, the single-particle spectral weight is reduced in a finite energy interval around the Fermi energy. The increase of U opens a gap between the occupied and unoccupied parts of the spectral function.