ES22-Edossa

Author: Edossa, Teshome Gerbaba - Department of Physics, College of Natural and Computational science, Wachemo University, Hosanna, Ethiopia

Title: Study of Electronic, Structural and Optical properties of Cadmium Sulfide (CdS) in Zinc-Blende and Wurtizite phase using DFT and DFT+U

Abstract: Zinc-blende(zb) and wurtzite(wz) structure of CdS was analyzed using DFT within LDA, PBE, GGA+U, and PBE0. To assure the accuracy of calculation, the convergence test of total energy with respect to energy cutoff and k-point sampling is performed. The relaxed atomic position for the CdS in zb and wz structure is obtained by using total energy and force minimization method following the Hellmann Feynman approach. The structural optimization and electronic band structure properties of CdS are investigated. Analysis of the results shows that LDA and PBE underestimate the band-gap due to their poor approximation of exchange-correlation functional. However, the DFT+U and the PBE0 approximation give a good band-gap value which is comparable to the experimental result. Moreover, Optical properties: complex and real parts of dielectric function, static dielectric function, energy-loss spectrum, absorption coefficient and refractive index of CdS in both zb and wz phase were studied within LDA, GGA and DFT + U to characterize its optical nature. Accuracy is found for the calculated values within DFT+U and PBE0 approximation. It is found that the wz-CdS exhibits anisotropy in two directions (in basal plan and z-axis).