Studies On The Electronic Structures And Optical Properties Of SrPtAs And SrPt2As2from First-principles

In this thesis the anisotropic optical properties for superconductor SrPtAs and three different structures of SrPt2As2have been studied by full-potential linearized augmented plane wave (FLAPW) method based on density functional theory. In order to simulate the temperature effects in these spectra, Lorentzian broadening (set as δ=0.10eV) is added into optical matrix elements during the calculation. The spectra of reflectivity R(ω), absorbtion, optical conductivity σ(ω) and electron energy loss have been calculated. And optical conductivity spectra along xx-axis display quite different features in comparison with that of zz-axis. Along xx-axis, σ(ω) spectra shows a obvious Drude-like feature in the low energy region while it doesn’t along zz-axis. The convert between intra-band absorption and inter-band absorption appears about0.88eV in the σ(ω) spectra along xx-axis, while0.7eV in the σ(ω) spectra along zz-axis. The anisotropic optical properties for three different structures of SrPt2As2are different. The anisotropy of SrPt2As2with CaBe2Ge2structure is obvious than that of two different SrPt2As2with ThCr2Si2structure. The convert between intra-band absorption and inter-band absorption appears about0.75eV、1eV、0.4eV respectively, while0.25eV、0.75eV、0.45eV in the σ(ω) spectra along zz-axis.