正交CaTiO_3电子结构及光学性质的第一性原理研究

First Principles Study on Electronic Structure and Optical Property in Orthorhombic CaTiO_3

基于密度泛函理论,采用第一性原理投影缀加波方法(PAW),应用广义梯度近似(GGA)处理交换关联能,计算了正交Ca Ti O3块体材料的晶格参数、电子能带结构、态密度和光学性质。几何优化结果获得的晶格参数和原子坐标与已有的理论和实验数据很吻合。研究表明,正交Ca Ti O3是带隙为2.43 e V,价带顶和导带底都在Γ点的直接带隙半导体,价带顶和导带底主要由Ti-3d,O-2p态杂化而成。另外,计算了正交Ca Ti O3的吸收光谱,发现在波长较短的紫外光波段有一强烈吸收峰,基于能带和态密度分析了吸收光谱与电子跃迁间的关系,为正交Ca Ti O3的应用提供了理论依据。

Based on the density-functional theory,the structural parameters,electronic structure and optical properties of orthorhombic CaTiO3 have been studied by using the first principle projector-augmented wave （PAW） method and the generalized gradient approximation （GGA） treatment of exchange correlation energy. The calculated structural parameters of orthorhombic CaTiO3 coincide well with the experimental orthorhombic data. The energy band structure and density of states are obtained,which indicates that orthorhombic CaTiO3 is a direct gap semiconductor with a band gap of 2.43 eV at Γ （gamma） point. Furthermore,the absorption coefficient of orthorhombic CaTiO3 has been calculated,which shows that there is a strong absorption in UV light band. Based on the band structure and density of states,the mechanism of the optical transitions for orthorhombic CaTiO3 is explained,which provides a theoretical basis for application of orthorhombic CaTiO3.