Metal-insulator transition in the two-dimensional Hubbard model: Dual fermion approach with Lanczos exact diagonalization
Metal-insulator transition in the two-dimensional Hubbard model: Dual fermion approach with Lanczos exact diagonalization
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DOI：
10.1103/physrevb.99.205133
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发表时间：
2019-05-20
影响因子：
3.7
通讯作者：
Tanaka, Arata
中科院分区：
文献类型：
--
作者：
Tanaka, Arata
本文利用梯形对偶费米子近似（LDFA）重新讨论了正方晶格Hubbard模型中半填充时金属-绝缘体相变与态密度和谱函数的关系。为此，提出了一种新的二体绿色函数的预解式表达式，为用Lanczos精确对角化（艾德）方法计算局部顶点函数提供了一种简便有效的方法.这使得有可能使用Lanczos艾德方法作为LDFA的有效杂质安德森模型的求解器，开辟了访问这些微扰扩展的动力学平均场理论的低温和获得准确的DOS和频谱函数的真实的频率轴上的最大熵方法的一个新的变种。结果表明，当U = 4.0t时，费米面上的费米液体特征在高温下已经部分丧失，这与Mott-Heisenberg区域中的情况相同，在该区域中，局部自旋在高温下形成.一个尖锐的交叉从pseudogap阶段的莫特绝缘体在有限U* 近似4.7吨被发现发生的pseudogap形成类似于以前的研究与非线性模型方法的温度以下。
In this study, the metal-insulator transition in the square-lattice Hubbard model at half-filling is revisited in relation to the DOS and spectral functions by means of the ladder dual fermion approximation (LDFA). For this purpose, a new expression of the two-body Green's function in the form of resolvents is proposed, which provides tractable and efficient means to calculate the local vertex function with the Lanczos exact diagonalization (ED) method. This makes it possible to use the Lanczos ED method as a solver of the effective impurity Anderson model for LDFA, opening up the way to access low temperatures for these perturbative extensions of the dynamical mean-field theory and to obtain accurate DOS and spectral functions on the real frequency axis by a new variant of the maximum entropy method. It is found that for U = 4.0t, the Fermi-liquid feature is partially lost on the Fermi surface already at higher temperatures as expected in the Mott-Heisenberg regime, in which local spins are preformed at high temperatures. A sharp crossover from a pseudogap phase to a Mott insulator at finite U* approximate to 4.7t is found to occur below the temperature of the pseudogap formation similar to a previous study with the nonlinear a model approach.