Numerical investigation of the validity of the Slater-Janak transition-state model in metallic systems -: art. no. 134203
Numerical investigation of the validity of the Slater-Janak transition-state model in metallic systems -: art. no. 134203
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DOI：
10.1103/physrevb.72.134203
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发表时间：
2005-10-01
影响因子：
3.7
通讯作者：
Abrikosov, IA
中科院分区：
文献类型：
--
作者：
Göransson, C;Olovsson, W;Abrikosov, IA
根据所谓的Janak定理，Kohn-Sham哈密顿量的本征态是由总能量相对于相应单电子态的占位数的导数给出的。通常假定Kohn-Sham本征值与占位数的线性依赖关系，以便在应用Janak定理时使用，例如，在利用Slate-Janak过渡态模型计算材料的芯能级移动时。为了验证线性假设，本文采用第一性原理密度泛函理论计算了24个不同随机合金系统中不同芯态的非整数占位数。研究发现，在一次近似下，Kohn-Sham本征值表现出与占据数成正比的线性行为。然而，研究还发现，对某些系统而言，偏离线性对核心电平漂移有显著影响。提出了一种在计算量最小的情况下减小误差的方法。
According to the so-called Janak's theorem, the eigenstates of the Kohn-Sham Hamiltonian are given by the derivative of the total energy with respect to the occupation numbers of the corresponding one-electron states. The linear dependence of the Kohn-Sham eigenvalues on the occupation numbers is often assumed in order to use the Janak's theorem in applications, for instance, in calculations of the core-level shifts in materials by means of the Slater-Janak transition state model. In this work first-principles density-functional theory calculations using noninteger occupation numbers for different core states in 24 different random alloy systems were carried out in order to verify the assumptions of linearity. It is found that, to a first approximation, the Kohn-Sham eigenvalues show a linear behavior as a function of the occupation numbers. However, it is also found that deviations from linearity have observable effects on the core-level shifts for some systems. A way to reduce the error with minimal increase of computational efforts is suggested.