Simulating Surface Spectroscopy of Single Atom Magnets and Catalysts

用于催化和磁光学应用的功能材料通常包含珍贵的材料，其稀缺性是最大限度地提高其使用效率的强烈动机。单原子可以作为催化剂（单原子催化剂，SACs）或单原子磁铁（SAMs），当稳定在明确的底物。SAC/SAM材料通常使用x射线光电子能谱和x射线吸收能谱进行研究，但其丰富的结构和重叠特征使得这些光谱难以解结。该项目将开发新的模拟方法来预测这种复杂的光谱特征，并与实验伙伴合作，对新型SAM和SAC材料进行表征。用于催化和磁光学应用的功能材料通常包含珍贵的材料，其稀缺性是最大限度地提高其使用效率的强烈动机。这可以通过降低贵金属原子的浓度来实现，同时保留甚至改善它们作为反应性或磁性中心的功能。在极端情况下，单原子可以作为催化剂（单原子催化剂，SACs）或单原子磁铁（SAMs），当稳定在明确定义的衬底上时。[1,2] x射线光电子能谱（XPS）、x射线吸收能谱（XAS）和x射线磁圆二色性（XMCD）在表征稳定单原子的结构、电子和磁态方面发挥着重要作用。实验XPS和NEXAFS光谱中存在丰富的结构和重叠特征，这往往给所有峰的明确分配带来挑战。在这里，对电子结构和核心层跃迁的理论分析和计算模拟可以产生新的见解。基于第一性原理的核能级光谱模拟已经建立，然而，几乎所有实用的电子结构方法都只能可靠地预测源自1s态激发的光谱。实验上，单金属原子的电子态和磁态最好的表征是探测具有更高角动量的核心态，如2p、3d或4f型轨道，而模拟技术仍然缺乏。在本项目中，您将开发一种有效但近似的方法来模拟2p， 3d和4f态的核心能级光谱，这对于分析sam和sac的化学和磁性状态非常重要。在与实验伙伴的合作下，新方法将应用于理解高磁矩表面支持的单原子的x射线光谱实验。新方法将在一个已建立的电子结构软件包中开发，通过结合最先进的自旋轨道耦合、强相关和核孔约束方法。

Functional materials for catalysis and magnetooptical applications often contain precious materials, the scarcity of which is a strong motivation for maximizing the efficiency of their use. Single atoms can act as catalysts (Single atom catalysts, SACs) or single atom magnets (SAMs) when stabilized on well-defined substrates. SAC/SAM materials are often studied with X-ray photoelectron spectroscopy and X-ray absorption spectroscopy, but the rich structure and overlapping features make these spectra hard to disentangle. This project will develop new simulation methodology to predict such complex spectroscopic signatures and, in collaboration with experimental partners, novel SAM and SAC materials will be characterized.Functional materials for catalysis and magnetooptical applications often contain precious materials, the scarcity of which is a strong motivation for maximizing the efficiency of their use. This can be achieved by reducing the concentration of precious metal atoms while retaining or even improving their functionality as reactive or magnetic centres. In the extreme limit, single atoms can act as catalysts (Single atom catalysts, SACs) or single atom magnets (SAMs) when stabilized on well-defined substrates. [1,2]X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and X-ray magnetic circular dichroism (XMCD) play an important role in characterizing the structure, electronic and magnetic state of stabilized single atoms. The rich structure and overlapping features present in experimental XPS and NEXAFS spectra often provide a challenge to the unambiguous assignment of all peaks. Here, the theoretical analysis and computational simulation of the electronic structure and core-level transitions can yield new insights. The first-principles-based simulation of core-level spectra is established [3], however, almost all practical electronic structure methods can only reliably predict spectra originating from excitation of 1s states. Experimentally, the electronic and magnetic states of single metal atoms are best characterized by probing core-states with higher angular momentum, such as 2p, 3d or 4f-type orbitals, for which simulation techniques are still lacking.In this project, you will develop an efficient but approximate methodology to simulate core-level spectra of 2p, 3d and 4f states, which are important for the analysis of the chemical and magnetic state of SAMs and SACs. In collaboration with experimental partners, the new methods will be applied to understand X-ray spectroscopy experiments on surface-supported single atoms with high magnetic moments. The new methods will be developed within an established electronic structure software package by combining state-of-the-art methods for spin-orbit coupling, strong correlation, and core-hole constraints.