First-Principles Study of Structural, Optical, and Thermodynamic Properties of ZnIN2X^sub 4^ (X = Se, Te) Compounds with DC or DF Structure

Structural and optoelectronic properties of ZnIN2Se4 and ZnIN2Te4 compounds in defect chalcopyrite (DC) and defect famatinite (DF) structures have been calculated by the full-potential linearized augmented plane-wave (FP-LAPW) method within density functional theory (DFT) as implemented in the WIEN2K package. For the exchange correlation effects, we adopted the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) for structural calculations and the Tran-Blaha-modified Becke-Johnson (TB-mBJ) functional for electronic properties. The lattice parameters (a, c) and internal parameters (x, y, z) are in good agreement with available results. The band structures prove that these kinds of material have a direct bandgap ([Gamma]-[Gamma]) in both structures. Optical properties such as the dielectric function [straight epsilon](ω) and refractive index n(ω) were calculated in the energy range from 0 eV to 14 eV. Thermodynamic properties were also analyzed using the quasiharmonic Debye model.