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arXiv 1809.02556physics.chem-ph
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激发态的多参考代数图解构造理论:一般公式和一阶实现

Multi-reference algebraic diagrammatic construction theory for excited states: General formulation and first-order implementation

Alexander Yu. Sokolov

摘要:

我们提出了一个多参考推广的代数图解构造理论(ADC)[J. Schirmer,物理修订A 26,2395(1982)]的激发电子态。由此产生的多参考ADC的方法(MR-ADC)可以有效地和可靠地应用于系统,表现出强的电子相关的基态或激发电子态。与传统的多参考微扰理论相比,MR-ADC描述了涉及所有轨道(核心,活性和外部)的电子跃迁,并能够有效计算光谱特性,如跃迁幅度和光谱密度。我们的MR-ADC的推导是基于Mukherjee和Kutzelnigg [D. Mukherjee,W. Kutzelnigg,量子化学中的多体方法(1989),pp. 257- 274],我们将其推广到多决定参考态。我们讨论了MR-ADC的一般公式,进行了微扰分析,并提出了一阶MR-ADC近似的实现,称为MR-ADC(1),作为定义MR-ADC方法层次的第一步。我们给出了Be原子的激发能、LiF中的避免交叉、C2中的双激发态的MR-ADC(1)结果,并概述了我们未来发展的方向。

英文摘要:

We present a multi-reference generalization of the algebraic diagrammatic construction theory (ADC) [J. Schirmer, Phys. Rev. A 26, 2395 (1982)] for excited electronic states. The resulting multi-reference ADC approach (MR-ADC) can be efficiently and reliably applied to systems, which exhibit strong electron correlation in the ground or excited electronic states. In contrast to conventional multi-reference perturbation theories, MR-ADC describes electronic transitions involving all orbitals (core, active, and external) and enables efficient computation of spectroscopic properties, such as transition amplitudes and spectral densities. Our derivation of MR-ADC is based on the effective Liouvillean formalism of Mukherjee and Kutzelnigg [D. Mukherjee, W. Kutzelnigg, in Many-Body Methods in Quantum Chemistry (1989), pp. 257--274], which we generalize to multi-determinant reference states. We discuss a general formulation of MR-ADC, perform its perturbative analysis, and present an implementation of the first-order MR-ADC approximation, termed MR-ADC(1), as a first step in defining the MR-ADC hierarchy of methods. We show results of MR-ADC(1) for the excitation energies of the Be atom, an avoided crossing in LiF, doubly excited states in C2, and outline directions for our future developments.

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