立方钙钛矿RbZnF3电子、弹性和光学性质的第一性原理研究
First principles study of electronic, elastic and optical properties of cubic perovskite RbZnF3

基于密度泛函理论和赝势平面波方法研究了立方钙钛矿RbZnF3的电子结构和光学性质；利用静水有限应变技术计算研究了RbZnF3弹性常数Cij、体积弹性模量B和剪切模量G随压力的变化关系。基态下，RbZnF3晶格常数a和体积弹性模量B0计算值与实验值以及其他理论值一致。根据能带结构、总态密度以及分波态密度分析可知：基态下立方钙钛矿结构RbZnF3为间接带隙半导体材料，带隙为3.57eV，与其他计算结果比较，本文计算结果偏低，这是由于局域密度近似(LAD)或广义梯度近似(GGA)交换关联函数的局限性所致。基态下RbZnF3的Mulliken电荷分布和集居数说明：RbZnF3属于共价键和离子键所形成的混合键化合物；RbZnF3的电荷总数主要来源于Rb 4s和4p轨道，Zn 3d轨道，以及F 2s和2p轨道。电荷主要从Rb, Zn原子向F原子转移。同时，本文还计算研究了RbZnF3的光学介电函数、吸收系数、复折射率、能量损失谱和反射系数等光学性质。
The electronic, elastic and optical properties of cubic perovskite RbZnF3 were investigated using the pseudo-potential plane wave method within the density functional theory. The elastic constants Cij, bulk modulus B and shear modulus G, and their pressure dependence were calculated using the static finite strain technique. The calculated equilibrium lattice a and bulk modulus B0 are in a reasonable agreement with the experimental and other theoretical data. According to the band structural theory, we have studied the band structure, total density of states (TDOS) and partial density of states (PDOS) for cubic perovskite RbZnF3 at ground state. The cubic perovskite RbZnF3 is an indirect band gap semi-conductive material, the value of the band gap is 3.57eV. The result is smaller than the literature, due to the well-known limitations of local density approximation (LDA) or generalized gradient approximation (GGA). At ground state, the Mulliken charge and population of cubic perovskite RbZnF3 were investigated. RbZnF3 is mix bond chemical compounds, which consist to ionic bond and covalent bond. The total charge of RbZnF3 derives from Rb 4s and 2p orbits, Zn 3d orbits, and F 2s and 2p orbits, respectively. At the same time, the dielectric function, adsorption coefficient, refractive index, loss function and reflection coefficient of RbZnF3 were calculated and investigated in this work.