from 28 June 2015 to 3 July 2015 (Africa/Johannesburg)
SAIP2015 Proceeding published on 17 July 2016
Exciton energies of chalcopyrites AgAlX2 (X=S,Se,Te) from GW and BSE calculations
Presented by Mr. Guy Moise DONGHO NGUIMDO on 30 Jun 2015 from 11:30 to 11:50
Type: Oral Presentation
Track: Track A - Division for Physics of Condensed Matter and Materials
Using state-of-the-art Density Functional and Many Body Perturbation Theories, we study electronic and optical properties of the chalcopyrites AgAlX 2 (X=S,Se,Te). The Kohn-Sham Density Functional Theory (DFT) underestimates the fundamental and the optical gaps as a result of the particle number dependant discontinuity in the exchange-correlation potential. Accurate estimates of fundamental gaps were obtained using post DFT Many Body Perturbation Theory at the GW level. Optical absorption spectra and optical gaps were determined from solutions of the Bethe- Selpeter Equation (BSE) in the Tamm-Damcoff approximation. Comparison of the BSE and the GW results were used to obtain exciton energies. The GW-level calculated bandgaps are in good agreement with experimental values. Exciton energies were estimated for the first time but we couldn’t find any theoretical or experimental results for comparison .
Daniel P. Joubert University of the Witwatersrand