自旋自适应开壳态含时密度泛函理论。第二部分：理论与初步应用。

Spin-adapted open-shell time-dependent density functional theory. II. Theory and pilot application.

机构信息

Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing, People's Republic of China.

出版信息

J Chem Phys. 2011 Apr 7;134(13):134101. doi: 10.1063/1.3573374.

DOI:10.1063/1.3573374

PMID:21476737

Abstract

The excited states of open-shell systems calculated by unrestricted Kohn-Sham-based time-dependent density functional theory (U-TD-DFT) are often heavily spin-contaminated and hence meaningless. This is solved ultimately by the recently proposed spin-adapted time-dependent density functional theory (TD-DFT) (S-TD-DFT) [J. Chem. Phys. 133, 064106 (2010)]. Unlike the standard restricted open-shell Kohn-Sham-based TD-DFT (R-TD-DFT) which can only access the singlet-coupled single excitations, the S-TD-DFT can capture both the singlet- and triplet-coupled single excitations with the same computational effort as the U-TD-DFT. The performances of the three approaches (U-TD-DFT, R-TD-DFT, and S-TD-DFT) are compared for both the spin-conserving and spin-flip excitations of prototypical open-shell systems, the nitrogen (N(2)(+)) and naphthalene (C(10)H(8)(+)) cations. The results show that the S-TD-DFT gives rise to balanced descriptions of excited states of open-shell systems.

摘要

基于非限制 Kohn-Sham 时变密度泛函理论 (U-TD-DFT) 计算的开壳层体系的激发态常常受到严重的自旋污染，因此毫无意义。这一问题最终通过最近提出的自旋自适应时变密度泛函理论 (TD-DFT) (S-TD-DFT) [J. Chem. Phys. 133, 064106 (2010)] 得到解决。与只能访问单重态耦合单激发的标准受限开壳层 Kohn-Sham 基 TD-DFT (R-TD-DFT) 不同，S-TD-DFT 可以用与 U-TD-DFT 相同的计算工作量捕获单重态和三重态耦合的单激发。比较了三种方法 (U-TD-DFT、R-TD-DFT 和 S-TD-DFT) 在典型开壳层体系氮 (N(2)(+)) 和萘 (C(10)H(8)(+)) 阳离子的自旋守恒和自旋翻转激发中的性能。结果表明，S-TD-DFT 导致了对开壳层体系激发态的平衡描述。