标题： 相对论嵌入运动方程耦合簇方法研究锕系元素的内层离子化状态：铯中铀酰(VI)的案例研究$_2$UO$_2$Cl$_4$ 显示英文标题

标题： Relativistic Embedded Equation-of-Motion Coupled-Cluster Approach to the Core-Ionized States of Actinides: A Case Study of Uranyl(VI) in Cs$_2$UO$_2$Cl$_4$

摘要： 我们研究了裸铀酰离子 (UO$_2^{2+}$) 的核心能级电离能及其在 Cs$_2$UO$_2$Cl$_4$晶体环境中的 X 射线相互作用，使用了最近实现的核心-价电子分离相对论方程-运动耦合簇方法 (CVS-EOM-CC)。 我们的研究评估了不同的相对论哈密顿量，评估了基组和虚拟空间截断的影响，并检查了轨道相关性和弛豫在模拟光谱可观测值中的作用。 本研究的结果突显了在软 X 射线和硬 X 射线范围内工作时，计算超越零阶截断（即库仑项）的双电子相互作用的重要性。 此外，我们使用冻结密度嵌入方法 (FDE) 比较了不同的结构模型。 通过对比裸铀酰模型和嵌入模型，我们观察到结合能的显著变化，突显了铀酰离子的赤道配体对其光谱可观测值的影响。 嵌入铀酰模型与排除铯原子的超分子系统的比较显示了系统性差异，结合能的变化与实验数据保持在 10 eV 以内。 值得注意的是，计算得到的 U$4d$和$4f$的自旋-轨道分裂偏差小于 0.7 eV，证明了该协议在软 X 射线范围计算结合能的有效性。 显示英文摘要

摘要： We investigate the core-level ionization energies of the bare uranyl ion (UO$_2^{2+}$) and its interaction with X-rays when it is hosted in the Cs$_2$UO$_2$Cl$_4$ crystalline environment using a recent implementation of the core-valence-separated relativistic equation-of-motion coupled-cluster method (CVS-EOM-CC). Our study evaluates different relativistic Hamiltonians, assesses basis set and virtual space truncation effects, and examines the role of orbital correlation and relaxation in simulating the spectroscopic observables. The results of this investigation highlight the importance of computing two-electron interactions beyond the zeroth-order truncation (i.e. the Coulomb term) when working in the tender and hard X-ray ranges. Additionally, we compare different structural models using the frozen density embedding method (FDE). By contrasting the bare and embedded uranyl models, we observe significant changes in binding energies, highlighting the influence of the equatorial ligands of the uranyl ion on its spectroscopic observables. A comparison between the embedded uranyl and supermolecular systems, excluding the cesium atoms, reveals systematic differences, with binding energy variations from experimental data remaining within 10 eV. Notably, the computed spin-orbit splittings for U $4d$ and $4f$ deviate by less than 0.7 eV, demonstrating the validity of this protocol for computing binding energies in the soft X-ray range.