Ground-state properties of rare-earth metals: an evaluation of density-functional theory
Ground-state properties of rare-earth metals: an evaluation of density-functional theory
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DOI：
10.1088/0953-8984/26/41/416001
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发表时间：
2014-10-15
影响因子：
2.7
通讯作者：
Lordi, V.
中科院分区：
文献类型：
--
作者：
Soederlind, Per;Turchi, P. E. A.;Lordi, V.
稀土金属由于其磁性而具有重要的技术应用，但稀缺且昂贵。开发低稀土含量的高性能磁性材料是迫切需要的，但稀土电子结构的复杂性阻碍了理论建模。在价带附近相关（类原子）4f电子的存在使得任何第一性原理理论都具有挑战性。本文将密度泛函理论应用于镧系元素（稀土）中，并对其电子交换和相关泛函、自旋轨道相互作用以及轨道极化的影响进行了研究。作为参考，结果与所谓的镧系元素的“标准模型”进行了比较，其中电子被限制在4f核态，与价电子没有杂化。还与为强电子相关性设计的模型进行了一些比较。我们的结果表明，自旋轨道耦合和轨道极化是重要的，特别是对磁矩的大小，并且计算的平衡体积，体积模量和磁矩总体上显示正确的趋势。然而，计算性质的精度还没有达到元素周期表中更简单金属的水平，电子结构也不能准确地再现x射线光发射光谱。
The rare-earth metals have important technological applications due to their magnetic properties, but are scarce and expensive. Development of high-performance magnetic materials with less rare-earth content is desired, but theoretical modeling is hampered by complexities of the rare earths electronic structure. The existence of correlated (atomic-like) 4f electrons in the vicinity of the valence band makes any first-principles theory challenging. Here, we apply and evaluate the efficacy of density-functional theory for the series of lanthanides (rare earths), investigating the influence of the electron exchange and correlation functional, spin-orbit interaction, and orbital polarization. As a reference, the results are compared with those of the so-called 'standard model' of the lanthanides in which electrons are constrained to occupy 4f core states with no hybridization with the valence electrons. Some comparisons are also made with models designed for strong electron correlations. Our results suggest that spin-orbit coupling and orbital polarization are important, particularly for the magnitude of the magnetic moments, and that calculated equilibrium volumes, bulk moduli, and magnetic moments show correct trends overall. However, the precision of the calculated properties is not at the level of that found for simpler metals in the Periodic Table of Elements, and the electronic structures do not accurately reproduce x-ray photoemission spectra.