Variational Monte Carlo Studies of Attractive Hubbard Model. I Normal-State Properties
Variational Monte Carlo Studies of Attractive Hubbard Model. I Normal-State Properties
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有吸引力的哈伯德模型的变分蒙特卡罗研究。
DOI：
10.1143/ptp.108.59
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发表时间：
2002
影响因子：
--
通讯作者：
H. Yokoyama
中科院分区：
文献类型：
--
作者：
H. Yokoyama
本文研究了从费米液体到绝缘态或带隙态的过渡过程中吸引力Hubbard模型的正常态，主要是二维的。本文用一系列统计性质较好的变分蒙特卡罗方法精确地估计了几种多体波函数的期望值。虽然观察到一个相对明显的交叉，即使是普通的Gutzwiller波函数，在这两个制度的国家是金属。与此同时，一个实质性的金属-绝缘体转变发生在|U|通过考虑无限域中二阶微扰的虚态，引入了一个改进的波函数，|U|极限该临界值与最近的动态平均场近似的结果相比毫不逊色。相比之下，传统的贾斯特罗型波函数几乎没有改善正常状态。此外，Brinkman-Rice金属-绝缘体转变的问题被重新考虑与更大的系统。
Normal states of the attractive Hubbard model, mainly in two dimensions, are studied in the context of a transition froma Ferm i liquid to an insulating or gapped state. A series of variational Monte Carlo calculations with better statistics was carried out to estimate accurately the expectation values of several many-body wave functions. Although a relatively clear crossover is observed, even for the plain Gutzwiller wave function, the states in both regimes are metallic. Meanwhile, a substantial metal-insulator transition takes place at |U |∼ W (band width) for an improved wave function, into which an intersite correlation is introduced by taking account of virtual states in the second-order perturbation in the infinite |U | limit. The critical value compares favorably with recent results of the dynamicalmean-field approximation. In contrast, a conventional Jastrow-type wave function scarcely improves the normal state. In addition, the issue of the Brinkman-Rice metal-insulator transition is reconsidered with much larger systems.