稀土La掺杂CrSi_2电子结构与光学性质的第一性原理研究

First principle study on electronic structure and optical properties of CrSi_2 doped rare earth element La

基于密度泛函理论的第一性原理赝势平面波方法,对稀土La掺杂CrSi2的几何结构,电子结构和光学性质进行了计算与分析.结果表明,La掺杂后,CrSi2的晶格常数a,b和c均增大,晶格体积增大.La掺杂导致费米面进入价带,带隙明显变窄仅为0.07eV;在费米面附近,La原子的5d层电子态密度只占总态密度很小的一部分,而总态密度仍然由Si的3p层和Cr的3d层电子的分波态密度决定;La掺杂后CrSi2的静态介电常数ε1(0)由28.98增大为91.69,ε2(ω)的两个介电峰均向低能方向偏移且增强,光学吸收边向低能方向移动,吸收峰减小.计算结果为CrSi2材料掺杂改性的实验研究提供了理论依据.

By using the first principle pseudo-potential plane-wave method based on the density function theory, the geometrical structure,electronic structure and optical properties for CrSi2 doped rare earth element La are calculated and analyzed.The calculated results show that the lattice constants a ,b ,c increase,the volume of lattice expands.The Fermi energy moves to the valences bands and the band gap narrows to 0.07eV with doped.The density of state near the Fermi energy level is mainly composed of Cr-3d and Si-3p,La-5d accounted for only a small part.The static dielectric constantε1 （0）increases significantly,from 28.98 to 91.69. The peak ofε2 （ω）increases and moves to a lower energy,the optical absorption edge also moves to a lower energy,and the peak of optical absorption coefficient decreases.These results offer experimental and theoretical data for do-ping of CrSi2.