SAIP2012

Theoretical calculation of positron states and annihilation rates in BaF₂

10 Jul 2012, 17:30

2h

IT Building

Poster Presentation Track A - Division for Condensed Matter Physics and Materials Poster Session

Speaker

Mr Thulani Jili (University of Zululand)

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

No

Abstract content <br> &nbsp; (Max 300 words)

Theoretical calculations for electronic structure are a valuable technique in the analysis of positron annihilation experiments. Theoretical calculations predict measured quantities such as annihilation rates and momentum distributions of annihilating electron-positron pair corresponding to vacancy-type defects trapping free positrons. Core electron annihilations are explained using free atom wavefunctions. The enhancement factor, g, was used in the Generalized Gradient Approximation (GGA) to influence both the fluorine and barium electronic annihilation rates. In the GGA, the annihilation rate in fluorine and barium ranges from 0.112 x 10⁹ s^-1 to 1.580 x 10⁹ s^-1 (1s – 2p) and from 0.011 x 10⁹ s^-1 to 2.017 x 10⁹ s^-1 (1s – 6s) respectively. Positron lifetimes of delocalized and localized positron in BaF₂ was calculated in the Two-component Density Functional Theory (TCDFT) and found to be 189.60 ps and 203.67 ps respectively. This is a confirmation of vacancy type defect at ambient temperature.

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

Yes