2019 Volume 127 Issue 1 Pages 50-55
Electronic structures and optical properties of CuMgVO4 and AgMgVO4 with optimized structures were investigated using the generalized gradient approximation proposed by Perdew-Burke-Ernzerhof and the Heyd-Scuseria-Ernzerhof hybrid functional. From the energy band calculation, we found that CuMgVO4 and AgMgVO4 have indirect band gaps. The upper valence band is mainly composed of fully occupied Cu 3d (Ag 4d) states, and the lower is mainly comprises O 2p states. The conduction band can be divided into two regions because of the crystal-field splitting by the interaction between the V 3d and the O 2p states. The optical properties of CuMgVO4 and AgMgVO4 were predicted from the complex dielectric function, ε(ω) = ε1(ω) + iε2(ω). The static dielectric constants were estimated from the real part of the dielectric functions, ε1(ω). The imaginary part of the dielectric functions, ε2(ω), demonstrated optical anisotropy, with the component along the z (y) direction being larger than the others for CuMgVO4 (AgMgVO4) in the wavelength range of visible light. The absorption coefficient I(ω) was also calculated from the dielectric function.