A density functional (PBE, PBEsol, HSE06) study of the structural, electronic and optical properties of the ternary compounds AgAlX

First principles density functional theory (DFT) calculations for bulk structural, electronic and optical properties of ternary compounds AgAlX2 (X = S, Se, Te) were performed with two flavours of generalised gradient approximations (PBE and PBEsol) and the hybrid functional HSE06. Using cohesive energy as a stability criterion, we found that the chalcopyrite structure is the favoured phase for these materials. PBEsol gives structural properties closer to the experimental values when compared to the results of PBE. Tetragonal distortion and anion displacement were calculated and we found them to be the cause of the crystal field splitting. Reduction of the bandgap and band splitting around the Γ in the Brillouin zone was noted when spin-orbit coupling was included in our study especially in the case of AgAlTe2. The HSE06 bandgap and frequency dependent dielectric function were in very good agreement with experimental results. We have also shown that the maximum absorption peak lies in the ultraviolet range irrespective of the functional used. The refractive index is also discussed

Electronic properties and defect levels induced by group III substitution–interstitial complexes in Ge

Please read abstract in the article.This work is based on the research supported partly by National Research Foundation (NRF) of South Africa (Grant specific unique reference number (UID) 98961).http://link.springer.com/journal/108532020-08-01hj2019Physic

Stability, electronic and defect levels induced by substitution of Al and P pair in 4H–SiC

Please read the abstract in the article.The National Research foundation (NRF) of South Africa, the University of South Africa (UNISA) and the Center for High Performance Computing (CHPC) Cape Town.http://www.elsevier.com/locate/jpcshj2021Physic