基于第一性原理计算压强对CaO电子结构和光学性质的影响

Pressure effect on the electronic structure and optical properties of CaO based on first-principles calculations

为了探究压强对CaO晶体电子结构和光学性质的影响,采用基于密度泛函理论的第一性原理平面波赝势理论方法对晶体进行了理论计算与分析.优化后所得晶格常数与实验值基本一致.研究结果表明:该晶体属于直接带隙绝缘体,带隙值为4.239 eV,价带顶主要由O-p轨道贡献,导带底由Ca-d轨道贡献.随着压强的增加,介电函数实部和折射率峰值减小,并发生红移,介电函数虚部峰值变大,并发生蓝移,而反射率、吸收系数和能量损失函数的峰值均增大.因此,改变压强可以有效改变CaO的电子结构和光学性质.

To investigate the effect of changing pressure on electronic structure and optical properties of CaO crystal, the theoretical calculation and prediction of the crystal were carried out by using the first principles plane wave pseudo potential theory method based on density functional theory. The lattice constants obtained by the optimized method were basically consistent with the experimental values. The calculated results show that the crystal belongs to the indirect band gap insula-tor, the band gap value is 4.239 eV, the valence band top is mainly contributed by the O-p orbit, and the bottom of the conduction is contributed by the Ca-d rail. With the increase of the pressure, the real part of dielectric function and the peak value of refractive index decrease and red shift occurs, the peak value of imaginary part of dielectric function increase and the blue shift occurs, while the reflectivity, absorption coefficient and energy loss-function increase. Therefore, the change of the pressure can effectively change the electronic structure and optical properties of CaO.