MgB2各向异性光学性质的第一性原理研究

使用密度泛函第一性原理研究了超导体MgB₂单晶各向异性的光学性质.在描述光学性质的基本理论和计算方法的基础上，计算了MgB₂的光电导谱、反射谱以及电子能量损失谱，并通过MgB₂的各个原子分解态密度图对所得到的反射谱和损失谱的各个谱峰做了详尽地分析.从光电导谱上来看，x方向与z方向有着很大差别，而在反射谱与电子能量损失谱中，x方向与z方向的特征峰位置都是相互符合的.从光导谱来看，沿关键词：超导体电子结构光学性质

Ab initio investigation of anisotropic optical properties of MgB2

The density functional theory and full-potential linearized augmented plane wave (FLAPW) method are used to study the anisotropic optical properties of superconductor MgB₂. The optical conductivity spectra，the reflectivity spectra and electron energy loss spectra have been calculated. The calculated optical conductivity spectra along xx-axis display quite different features in comparison with that along the zz-axis，while the reflectivity spectra coincide well with the corresponding electron energy loss spectra，especially with respect to the characteristic peaks. In the optical conductivity spectra，the first intra-band absorption peak along xx-axis appears at 20000cm^-1 while along zz-axis it appears at a high frequency of about 40000cm^-1. In order to simulate the temperature effect in these spectra，the Lorentz expansion (δ=0.10eV) is added to the optical matrix elements in the calculation for 0K. In comparison with existing experimental data，a minor discrepancy of 1000cm^-1 (～0.124eV) has been found in the calculated optical spectra.