紧密结合
原子轨道的线性组合
原子轨道
电子结构
特征向量
哈密尔顿矩阵
基准集
哈密顿量(控制论)
高斯分布
化学
计算化学
电子能带结构
化学吸附
量子力学
物理
数学
物理化学
密度泛函理论
电子
对称矩阵
数学优化
吸附
摘要
A brief discussion of first principles extended tight binding (ETB) (also known as linear combination of atomic orbitals, LCAO) method for studying electronic structure of solids is presented. As the name suggests, the method is nonempirical and employs a linear combination of Bloch-adapted Gaussian orbitals as its basis set. Hamiltonian and overlap matrix elements required for calculating electronic structure in solids can be obtained analytically using Gaussian functions. Various matrix elements are computed to convergence (which may involve interactions up to 10–12 neighbors), eigenvalues and eigenvectors are obtained by solving ∥H−ES∥−0. Since the tight binding wave functions are constructed from s, p, d, ... type of orbitals, the ETB method offers conceptual simplicity in understanding the nature of chemical bonds at a surface. Furthermore, the identification of surface states can be readily accomplished in terms of atomic localization, a quantity which is straightforward to calculate within the framework of this method. The method is illustrated by (i) absorbate band formation in CO monolayers and (ii) chemisorption studies of Cl on Si(111) surface. Future likely developments of the ETB method are briefly commented upon.
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