a2Si电子结构和光学性质的研究

By using the first principle methods based on plane-wave pseudo-potential theory, electronic structure and optical properties of Ca2Si both orthorhombic and cubic are investigated, including band structure, the density of states, the dielectric function. The results of calculation reveal that they are semiconductors. A direct gap and sizeable anisotropy in optical properties are found for orthorhombic Ca2Si. From band structure and density of states, we conclude that the optical properties of Ca2Si in the low energy region are caused by the interband transition from Si 3p electrons of the valence bands to the Ca 3d electrons of the conduction bands.