Multireference spin-adapted variant of density functional theory.
Multireference spin-adapted variant of density functional theory.
复制标题
密度泛函理论的多参考自旋适应变体。
DOI：
10.1063/1.1646352
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
M. Hoffmann
中科院分区：
文献类型：
--
作者：
Y. Khait;M. Hoffmann
开发了一种新的 Kohn-Sham 形式体系，用于研究给定空间和自旋对称性的最低分子电子态，其密度由几个参考配置的加权和表示。与标准自旋密度泛函理论不同，新形式主义使用总自旋守恒自旋密度算子和自旋不变密度矩阵，使得该方法完全自旋自适应并解决了所谓的自旋对称困境。该形式允许使用任意数量的开放壳的参考（非交互）配置集。结果表明，参考构型（或构型状态函数）的总非相互作用能量的简并性要求相当于精确能量相对于构型（或构型状态函数）权重的平稳条件。因此，在任何分子几何形状下，可以通过最小化能量来确定重量，并且对于给定的参考重量，可以确定 Kohn-Sham 轨道。从这个角度来看，所发展的理论可以解释为密度泛函理论中多配置自洽场方法的模拟。
A new Kohn-Sham formalism is developed for studying the lowest molecular electronic states of given space and spin symmetry whose densities are represented by weighted sums of several reference configurations. Unlike standard spin-density functional theory, the new formalism uses total spin conserving spin-density operators and spin-invariant density matrices so that the method is fully spin-adapted and solves the so-called spin-symmetry dilemma. The formalism permits the use of an arbitrary set of reference (noninteracting) configurations with any number of open shells. It is shown that the requirement of degeneracy of the total noninteracting energies of the reference configurations (or configuration state functions) is equivalent to the stationary condition of the exact energy relative to the weights of the configurations (or configuration state functions). Consequently, at any molecular geometry, the weights can be determined by minimization of the energy, and, for given reference weights, the Kohn-Sham orbitals can be determined. From this viewpoint, the developed theory can be interpreted as an analog of the multiconfiguration self-consistent field approach within density functional theory.