{ital Ab initio} estimate of Hubbard model parameters: A simple procedure applied to BEDT-TTF salts
{ital Ab initio} estimate of Hubbard model parameters: A simple procedure applied to BEDT-TTF salts
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哈伯德模型参数的 {ital Ab initio} 估计：应用于 BEDT-TTF 盐的简单程序
DOI：
10.1103/physrevb.55.16088
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发表时间：
1997
影响因子：
3.7
通讯作者：
A. Painelli
中科院分区：
文献类型：
--
作者：
A. Fortunelli;A. Painelli
我们描述了一个简单的过程，用于从二聚体单元的一组{ital ab initio}计算中提取单带哈伯德模型的参数。该方法适用于轨道弛豫可忽略不计的窄带固体。在本文中，我们考虑一个特定的系统，{kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Br，但所提出的程序具有普遍适用性。从对{ital ab initio}数据的详细讨论中，我们提取了一些关于经验模型参数的相对大小的广泛适用性的一般标准。我们证明，除了特定的几何排列之外，哈伯德模型（包括场内和场间电子-电子相互作用）对于轨道弛豫可忽略不计的系统来说是一个可靠的模型。跳跃参数（t）以及位点间电子斥力（V）几乎不受化学环境的影响。相反，通过前沿和核心能量对周围势的依赖，现场能量和现场排斥（哈伯德 h 和 U）显示出对化学环境的明显依赖性。 {版权} {ital 1997} {ital 美国物理学会}
We describe a simple procedure to extract the parameters of the one-band Hubbard model from a set of {ital ab initio} calculations on a dimeric unit. The method applies to narrow band solids with negligible orbital relaxation. In this paper we consider a specific system, {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Br, but the proposed procedure is of general applicability. From a detailed discussion of the {ital ab initio} data, we extract a few general criteria of wide applicability about the relative magnitude of the empirical model parameters. We prove that the Hubbard model, including both on-site and inter-site electron-electron interactions, is a reliable model for systems with negligible orbital relaxation, apart from particular geometrical arrangements. The hopping parameter (t), as well as the intersite electronic repulsion (V), are barely affected by the chemical environment. On the contrary, the on-site energy and the on-site repulsion (the Hubbard h and U) show an appreciable dependence on the chemical environment, through a dependence of the frontier and core energies on the surrounding potential. {copyright} {ital 1997} {ital The American Physical Society}