Kovács Péter, Tran Fabien, Blaha Peter, Madsen Georg K H
Institute of Materials Chemistry, Vienna University of Technology, Getreidemarkt 9/165-TC, A-1060 Vienna, Austria.
J Chem Phys. 2019 Apr 28;150(16):164119. doi: 10.1063/1.5092748.
The SCAN meta-generalized gradient approximation (GGA) functional is known to describe multiple properties of various materials with different types of bonds with greater accuracy, compared to the widely used PBE GGA functional. Yet, for alkali metals, SCAN shows worse agreement with experimental results than PBE despite using more information about the system. In the current study, this behavior for alkali metals is explained by identifying an inner semicore region which, within SCAN, contributes to an underbinding. The inner semicore push toward larger lattice constants is a general feature but is particularly important for very soft materials, such as the alkali metals, while for harder materials the valence region dominates.
与广泛使用的PBE广义梯度近似（GGA）泛函相比，已知SCAN元广义梯度近似（GGA）泛函能更准确地描述具有不同类型键的各种材料的多种性质。然而，对于碱金属，尽管SCAN使用了更多关于体系的信息，但与实验结果的吻合度却比PBE差。在当前的研究中，通过识别一个内层半芯区域来解释碱金属的这种行为，在SCAN中，该区域导致了结合不足。内层半芯向更大晶格常数的推动是一个普遍特征，但对于非常软的材料（如碱金属）尤为重要，而对于较硬的材料，价层区域起主导作用。
