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arXiv 2107.04196physics.chem-ph
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激发态的多参考代数图构造理论:扩展的二阶实现与基准

Multireference Algebraic Diagrammatic Construction Theory for Excited States: Extended Second-Order Implementation and Benchmark

Ilia M. Mazin, Alexander Yu. Sokolov

摘要:

我们提出了一个新的近似多参考代数图解构造理论的中性电子激发和UV/Vis光谱的强相关分子系统(MR-ADC)的模拟的实施和基准。在我们对一阶MR-ADC近似的研究[J. Chem. Phys. 2018,149,204113]之后,我们报告了严格和扩展的二阶MR-ADC方法(MR-ADC(2)和MR-ADC(2)-X),该方法结合了基态和激发电子态中静态和动态电子相关性的描述,而不依赖于状态平均参考波函数。我们提出了一个广泛的基准的新的MR-ADC方法的激发态在几个小分子,包括碳二聚体,乙烯和丁二烯。我们的结果表明,对于弱关联电子态,MR-ADC(2)和MR-ADC(2)-X方法优于三阶单参考ADC近似,并且与运动方程耦合团簇理论的结果具有竞争力.对于具有多参考特征的态,MR-ADC方法的性能与N电子价态微扰理论的性能相似。与传统的多参考微扰理论相比,MR-ADC方法具有许多有吸引力的特征,例如激发态性质的直接和有效的计算以及直接访问前沿(活性)轨道之外的激发。

英文摘要:

We present an implementation and benchmark of new approximations in multireference algebraic diagrammatic construction theory for simulations of neutral electronic excitations and UV/Vis spectra of strongly correlated molecular systems (MR-ADC). Following our work on the first-order MR-ADC approximation [J. Chem. Phys. 2018, 149, 204113], we report the strict and extended second-order MR-ADC methods (MR-ADC(2) and MR-ADC(2)-X) that combine the description of static and dynamic electron correlation in the ground and excited electronic states without relying on state-averaged reference wavefunctions. We present an extensive benchmark of the new MR-ADC methods for excited states in several small molecules, including the carbon dimer, ethylene, and butadiene. Our results demonstrate that for weakly-correlated electronic states the MR-ADC(2) and MR-ADC(2)-X methods outperform the third-order single-reference ADC approximation and are competitive with the results from equation-of-motion coupled cluster theory. For states with multireference character, the performance of the MR-ADC methods is similar to that of an N-electron valence perturbation theory. In contrast to conventional multireference perturbation theories, the MR-ADC methods have a number of attractive features, such as a straightforward and efficient calculation of excited-state properties and a direct access to excitations outside of the frontier (active) orbitals.

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