Ca2Si电子结构和光学性质的研究

采用第一性原理赝势平面波方法系统的计算了Ca2Si电子结构和光学性质，其中包括能带、态密度、介电函数、复折射率、吸收系数、光电导率和能量损失函数。计算结果显示Ca2Si是典型的半导体，正交相结构有一个直接的带隙，并且光学性质显示出各向异性。Ca2Si立方相的计算结果也显示是直接带隙半导体，并且有很高的振子强度。从能带和态密度的计算结果判断出它们的光学性质主要由Si的3p态电子向Ca的3d态的带间跃迁所决定。

The study on the electronic structure and optical properties of Ca2Si

By using the first principle methods based on plane-wave pseudo-potential theory, electronic structure and optical properties of Ca2Si both in the 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.