我们对 Ce L3 XANES 了解多少？多重态-连续谱边界上构型特异性屏蔽的从头算洞见
How Much Do We Understand Ce L3 XANES? Ab Initio Insights into Configuration-Specific Screening at the Multiplet--Continuum Frontier
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中文总结 AI 辅助
本研究通过 XSpectruplet 方法，揭示了 Ce L3 XANES 中集体屏蔽与局部多重态的相互作用，解释了 CeO2 和 CePO4 的光谱差异，表明集体再杂化可产生不同光谱贡献。
中文摘要 AI 辅助
局部多重态特征、集体芯空穴屏蔽和扩展光电子如何在 Ce $L_3$ X射线吸收近边光谱中协调一致？受 Kvashnina [Chem. Eur. J. 30, e202400755 (2024)] 提出的问题启发，我们使用 XSpectruplet 解决这一挑战，该方法在自洽 Kohn-Sham 屏蔽势中将局部多重态动力学与连续谱光电子传播耦合。对于 CeO$_2$ 中的 Ce$^{4+}$，我们的启发式搜索识别出主要和次要的稳态屏蔽态，在计入各自独立计算的总能量差后，其计算的白线最大值相距约 7.3 eV，但两者均保留相同的有效局部光谱 $4f^0$ 扇区。它们与未弛豫的突然参考态的平方重叠分别给出约 63% 和 30% 的近似统计权重（在独立通道描述内）。它们相反的屏蔽响应源于占据轨道的集体再杂化，而非额外的局域 $4f$ 旁观者占据，并在主白线和卫星区域均产生贡献。独居石 CePO$_4$ 中的 Ce$^{3+}$ 提供了对比案例，即局域 $4f^1$ 旁观者明确参与多重态动力学。中性 $4f$ 态和白线态的独立弛豫给出 CeO$_2$ 的前边-白线间隙为 10.51 eV，接近实验分离约 10.7 eV。其相对于固定背景光谱间隙的超出量定义了一个净修正，我们将其启发式地转移到 CePO$_4$，而不改变其局部多重态结构。这给出估计的 CePO$_4$ 间隙为 6.38 eV，而实验值约为 8.1 eV。因此，不同的光谱贡献可以源于集体屏蔽，而无需改变有效局部构型。
英文摘要
How can local multiplet signatures, collective core-hole screening, and an extended photoelectron be reconciled in Ce $L_3$ x-ray absorption near-edge spectra? Motivated by the question raised by Kvashnina [Chem. Eur. J. 30, e202400755 (2024)], we address this challenge using XSpectruplet, which couples local multiplet dynamics to continuum photoelectron propagation in self-consistent Kohn--Sham screening potentials. For Ce$^{4+}$ in CeO$_2$, our heuristic search identifies primary and secondary stationary screening states whose calculated white-line maxima lie about 7.3~eV apart after including their independently calculated total-energy difference, yet both retain the same effective local spectroscopic $4f^0$ sector. Their squared overlaps with the unrelaxed sudden reference give approximate statistical weights of 63\% and 30\%, respectively, within an independent-channel description. Their contrasting screening responses arise from collective rehybridization of occupied orbitals, rather than occupation of an additional localized $4f$ spectator, and produce contributions in both the main white-line and satellite regions. Ce$^{3+}$ in monazite CePO$_4$ provides the contrasting case of a localized $4f^1$ spectator participating explicitly in the multiplet dynamics. Independent relaxation of neutral $4f$ and white-line states gives a CeO$_2$ pre-edge--white-line gap of 10.51~eV, close to the experimental separation of approximately 10.7~eV. Its excess over the fixed-background spectral gap defines a net correction, which we transfer heuristically to CePO$_4$ without changing its local multiplet structure. This gives an estimated CePO$_4$ gap of 6.38~eV, compared with approximately 8.1~eV experimentally. Distinct spectral contributions can thus arise from collective screening without a change in the effective local configuration.
发表机构
- European Synchrotron Radiation Facility（欧洲同步辐射装置）
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