1. Mandelstam Institute for Theoretical Physics, University of the Witwatersrand, Johannesburg, Wits 2050, South Africa
2. School of Physics, University of the Witwatersrand, Johannesburg, Wits 2050, South Africa
3. National Institute for Theoretical Physics (NITheP), University of the Witwatersrand, Johannesburg, Wits 2050, South Africa
4. DST-NRF Centre of Excellence in Mathematical and Statistical Sciences (CoE-MaSS), University of the Witwatersrand, Johannesburg, Wits 2050, South Africa
5. Department of Chemistry and Physics, SUNY Old Westbury, Old Westbury, NY 11568, USA
6. Department of Physics, Virginia Tech, Blacksburg, VA 24061, USA