Excitation Energies of UO22+, NUO+, and NUN Based on Equation-of-Motion Coupled-Cluster Theory with Spin- Orbit Coupling
Excitation Energies of UO22+, NUO+, and NUN Based on Equation-of-Motion Coupled-Cluster Theory with Spin- Orbit Coupling
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基于自旋轨道耦合运动方程耦合团簇理论的UO22、NUO和NUN的激发能
DOI：
10.1021/acs.jpca.7b02985
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发表时间：
2017
影响因子：
2.9
通讯作者：
Wang Fan
中科院分区：
文献类型：
--
作者：
Zhang Shuo;Wang Fan
由于电子关联和自旋轨道耦合（SOC）的重要性，获得等电子系列，UO 22+，NUO+和UN 2的可靠激发能是量子化学计算中的一个挑战。本文采用耦合团簇运动方程方法（EOM-CCSD），在CC单双水平上计算了这些分子的垂直自旋自由能和自旋轨道耦合激发能。SOC被包括在SCF后计算中，并且这种处理已被证明可以提供具有高精度的重元素SOC效应。UO 22+的激发能与线性响应CCSD、多组态微扰理论（CASPT 2）和多参考组态相互作用（MRCI）的结果吻合得很好。至于NUO+和UN 2，从两个先前的计算与CASPT 2的激发能显着不同，目前的结果通常位于这两组CASPT 2的结果之间。另一方面，与我们的结果相比，中间Hamiltonian Fock空间CC方法（IHFSCC）的激发能通常太小。这一工作为研究大分子铀配合物的光谱和发光性质提供了新的理论依据。
Obtaining reliable excitation energies of the isoelectronic series, UO22+, NUO+, and UN2, is a challenge in quantum chemistry calculations due to importance of electron correlation and spin–orbit coupling (SOC). Vertical spin-free and spin–orbit coupled excitation energies of these molecules are calculated in this work using equation-of-motion coupled-cluster approach at the CC singles and doubles level (EOM-CCSD). SOC is included in post-SCF calculations and this treatment has been shown to provide SOC effects with high accuracy for heavy elements. Excitation energies for UO22+with the present approach are in good agreement with previous results using linear response CCSD, multiconfiguration perturbation theory (CASPT2), and multireference configuration interaction (MRCI). As for NUO+and UN2, excitation energies with CASPT2 from two previous calculations differ significantly and the present results usually lie between these two sets of CASPT2 results. On the other hand, excitation energies with intermediate Hamiltonian Fock space CC method (IHFSCC) are generally too small compared with our results. This work provides new estimates on excitation energies of these molecules and it could be helpful in investigating spectroscopic and luminescence properties of larger uranium complexes.