28 June 2015 to 3 July 2015
Africa/Johannesburg timezone
SAIP2015 Proceeding published on 17 July 2016

Exciton energies of chalcopyrites AgAlX2 (X=S,Se,Te) from GW and BSE calculations

30 Jun 2015, 11:30
20m
Oral Presentation Track A - Division for Physics of Condensed Matter and Materials DPCMM

Speaker

Mr Guy Moise DONGHO NGUIMDO (University of the Witwatersrand)

Please indicate whether<br>this abstract may be<br>published online<br>(Yes / No)

Yes

Main supervisor (name and email)<br>and his / her institution

Daniel P. Joubert University of the Witwatersrand

Apply to be<br> considered for a student <br> &nbsp; award (Yes / No)?

Yes

Would you like to <br> submit a short paper <br> for the Conference <br> Proceedings (Yes / No)?

Yes

Abstract content <br> &nbsp; (Max 300 words)<br><a href="http://events.saip.org.za/getFile.py/access?resId=0&materialId=0&confId=34" target="_blank">Formatting &<br>Special chars</a>

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 .

Level for award<br>&nbsp;(Hons, MSc, <br> &nbsp; PhD, N/A)?

PhD

Primary author

Mr Guy Moise DONGHO NGUIMDO (University of the Witwatersrand)

Co-authors

Prof. Daniel P. Joubert (University of the Witwatersrand) Mr Mahmud ABDULSALAM (University of Witwatersrand)

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