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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Tight-Binding Density Functional Theory: An Approximate Kohn-Sham DFT Scheme
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Tight-Binding Density Functional Theory: An Approximate Kohn-Sham DFT Scheme

机译：紧束缚密度泛函理论：近似Kohn-Sham DFT方案

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摘要

The DFTB method is an approximate KS-DFT scheme with an LCAO representation of the KS orbitals, which can be derived within a variational treatment of an approximate KS energy functional. But it may also be related to cellular Wigner-Seitz methods and to the Harris functional. It is an approximate method, but it avoids any empirical parametrization by calculating the Hamiltonian and overlap matrices out of DFT-derived local orbitals (atomic orbitals, AO's). The method includes ab initio concepts in relating the Kohn-Sham orbitals of the atomic configuration to a minimal basis of the localized atomic valence orbitals of the atoms. Consistent with this approximation, the Hamiltonian matrix elements can strictly be restricted to a two-center representation. Taking advantage of the compensation of the so-called "double counting terms" and the nuclear repulsion energy in the DFT total energy expression, the energy may be approximated as a sum of the occupied KS single-particle energies and a repulsive energy, which can be obtained from DFT calculations in properly chosen reference systems. This relates the method to common standard "tight-binding" (TB) schemes, as they are well-known in solid-state physics. This approach defines the density-functional tight-binding (DFTB) method in its original (non-self-consistent) version.
机译：DFTB方法是具有KS轨道的LCAO表示的近似KS-DFT方案，可以在近似KS能量函数的变分处理中得出。但这也可能与细胞Wigner-Seitz方法和Harris函数有关。这是一种近似方法，但它通过计算DFT衍生的局部轨道（原子轨道，AO）中的哈密顿量和重叠矩阵，避免了任何经验参数化。该方法包括从头开始的概念，其将原子构型的Kohn-Sham轨道与原子的局部原子价轨道的最小基础相关。与这种近似一致，哈密顿矩阵元素可以严格地限制为两中心表示。利用DFT总能量表达式中所谓的“双重计数项”和核排斥能量的补偿，可以将能量近似为所占据的KS单粒子能量和排斥能量的总和。从DFT计算中适当选择参考系统获得。这使该方法与通用标准“紧密绑定”（TB）方案相关联，因为它们在固态物理学中是众所周知的。此方法在其原始（非自洽）版本中定义了密度函数紧密绑定（DFTB）方法。

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