عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Electronic and optical properties of Cu2-II-IV-VI4(II=Zn,Cd; IV=Ge,Sn; VI=S,Se,Te) quaternary chalcogenides are calculated using the full potential linearized augmented plane wave (FP-LAPW) method within the density functional theory (DFT) and the calculated results are compared with the available experimental results. The real and imaginary parts of the dielecteric function ԑ(ω), the electron energy loss function (EELS) and the optical absorption coefficient I(ω) are calculated within the random phase approximation (RPA). The prominent structures in the specrta of ԑ1(ω), ԑ2(ω) and EELS are discussed in detail and the static dielectric constants of these compounds are calculated . The most prominent feature of these compounds is their high absorption coefficient and wide absorption spectrum. It is an appropriate parameter for using in solar cells. The band structures are calculated using Perdew et al., Engel-Vosko and modified Becke-Johnson schemes and the effect of the exchange-correlation functional on the band gap of these compounds is investigated. It is shown that mBJ-GGA leads to a better result.