β-CaSiO_3晶体的电子结构及光学性质

Study on the Electronic Structure and Optical Properties of β-CaSiO_3

基于第一性原理的平面波赝势方法(PWP)的局域密度近似(LDA)/广义梯度近似(GGA)计算了β-Ca-SiO3的几何结构、能带结构、态密度和光学性质。其晶胞参数优化结果与实验相比,LDA/GGA的相对误差为-3.62%/1.91%。对优化后的β-CaSiO3晶体进行能带结构分析表明,β-CaSiO3晶体为间接带隙结构,禁带宽度Eg(LDA)=5.53eV,Eg(GGA)=5.18eV。对态密度图及Mulliken电荷分布的分析表明,Ca的d轨道有电子分布,即Ca的s、p、d轨道均参与了成键。β-CaSiO3晶体中Ca与SiO3基团之间形成的化学键主要是离子键,而Si与O之间的化学键是共价键。

A first-principles pseudopotential plane-wave method based on LDA/GGA method of density functional theory was used to investigate the geometry structures, band structures, density of states and optical properties of β-CaSiO3. The results show that the lattice parameter of optimization is only --3. 62%/1. 91% （relative error （RE）） within the LDA/GGA method compared with the experimental results. Based on the analysis of the band structure of optimized β-CaSiO3 crystal with LDA/GGA approximation, it is found that indirect band gaps are 5.53eV/5.18 eV. Analyses of density of states and Mulliken electron population show that there is charge distribution in the d orbit of calcium atom, which means the s, p, d orbit of calcium participate in bonding. In β-CaSiO3, the ionic bond is formed between Ca and SiOa , while the covalent bond is formed between Si and O.