While new light sources allow for unprecedented resolution in experiments with X-rays, a theoretical understanding of the scattering cross-section is lacking. In the particular case of strongly correlated electron systems, numerical techniques are quite limited, since conventional approaches rely on calculating a response function (Kramers-Heisenberg formula) that is obtained from a perturbative analysis of scattering processes in the frequency domain. This requires a knowledge of a full set of eigenstates in order to account for all intermediate processes away from equilibrium, limiting the applicability to small tractable systems. In this work, we present an alternative paradigm, recasting the problem in the time domain and explicitly solving the time-dependent Schrödinger equation without the limitations of perturbation theory: a faithful simulation of the scattering processes taking place in actual experiments, including photons and core electrons. We show how this approach can yield the full time and momentum resolved Resonant Inelastic X-Ray Scattering (RIXS) spectrum of strongly interacting many-body systems. We demonstrate the formalism with an application to Mott insulating Hubbard chains using the time-dependent density matrix renormalization group method, which does not require a priory knowledge of the eigenstates and can solve very large systems with dozens of orbitals. This approach can readily be applied to systems out of equilibrium without modification and generalized to other spectroscopies.
Multichannel active-space embedding of atomic multiplets in plane-wave DFT/PAW for core-level spectroscopies
European Synchrotron Radiation Facility（欧洲同步辐射装置）；Univ. Grenoble Alpes, CNRS, IRD, Irstea, Météo France, OSUG, FAME（格勒诺布尔阿尔卑斯大学、法国国家科学研究中心、法国海外研究与发展局、法国国家农业食品与环境研究院、法国气象局）；Istituto per lo Studio dei Materiali Nanostrutturati, Consiglio Nazionale delle Ricerche（意大利国家研究委员会纳米结构材料研究所）
Elastic Scattering Susceptibility of the High Temperature Superconductor Bi2Sr2CaCu2O8+x: A Comparison between Real and Momentum Space Photoemission Spectroscopies
通过计算角分辨光电子能谱（ARPES）测量的单粒子谱函数A（k，ω）的自相关性，计算了Bi 2Sr 2CaCu 2 O 8 +x的联合态密度（JDOS）.这些结果进行了比较与傅立叶变换（FT）电导调制测量的扫描隧道显微镜（STM）。两个实验探针之间的良好协议被发现为两个不同的掺杂值检查。此外，通过将FT-STM结果与不同光子偏振态的自相关ARPES谱进行比较，对STM矩阵元的形式有了新的认识。这为隧道数据中未解之谜提供了新的线索。
Crystalline electric field effects in Ce 3$d$ core-level spectra of heavy-fermion systems: Hard X-ray photoemission spectroscopy on CeNi$_{1-x}$Co$_x$Ge$_2$
Effect of core-valence intra-atomic quadrupolar interaction in resonant x-ray scattering at the Dy M$_{4,5}$ edges in DyB$_2$C$_2$
采用考虑晶场效应的原子多重态哈密顿量，并在3d核与4f价壳层之间引入原子内四极相互作用，计算了DyB $_2$ C $_2$中$(00{1/2})$在Dy M $_{4,5}$边的共振软X射线Bragg衍射强度与能量的关系.将这些计算与实验结果（Mulders等人，J.物理学：康登斯Matter 18（2006）11195）在DyB $_2$ C $_2$的反铁四极和反铁磁相中。我们再现所有的功能出现$(00{1/2})$反射能量分布在反铁四极有序相，我们再现的行为的共振X射线散射强度在不同的能量附近的Dy M $_5$边缘时，温度降低反铁磁相。
