First-principles calculations of optical constants

The energy loss function (ELF) describes the interaction between electrons and matter in solids. It is essential for understanding quantitative surface analyses such as Auger electron and X-ray photoelectron spectroscopy. The optical constant and ELF, however, are unknown for most materials in the 20–50 eV energy range, where electron–solid interactions are strong, owing to experimental difficulties. We calculate and make a database of ELFs and optical constants using optical data of 35 inorganic semiconductors in a wide energy range (0.1 eV – 1 MeV) using first-principles calculations with FEFF and WIEN2k. The calculated ELFs for GaAs and InSb agree very well with the available experimental data. We evaluate the resulting 35 ELFs with two sum rules, the f-sum rule and the Kramers–Kronig sum rule. Their mean absolute errors are 1.6% and 0.05%, respectively. All data can be obtained from the materials data repository provided by the National Institute for Materials Science.

电子能量损失函数（energy loss function，ELF）用于描述固体中电子与物质的相互作用。其对于理解俄歇电子能谱、X射线光电子能谱等定量表面分析技术至关重要。然而，受限于实验难题，在电子与固体相互作用较强的20~50 eV能量区间内，多数材料的光学常数与ELF均缺乏有效数据。本研究依托FEFF与WIEN2k软件开展第一性原理计算，基于35种无机半导体在0.1 eV至1 MeV宽能量区间内的光学数据，计算得到其ELF与光学常数并构建了对应数据库。针对GaAs与InSb的计算所得ELF与已公开实验数据吻合度极佳。本研究采用f求和定则与克拉默斯-克勒尼希求和定则对所得的35组ELF进行评估，二者的平均绝对误差分别为1.6%与0.05%。所有数据均可通过国家材料科学研究所提供的材料数据仓库获取。