9-13 July 2012
Africa/Johannesburg timezone
<a href="http://events.saip.org.za/internalPage.py?pageId=11&confId=14"><font color=#ff0000>SAIP2012 PROCEEDINGS AVAILABLE</font></a>

Theoretical calculation of positron states and annihilation rates in BaF<sub>2</sub>

10 Jul 2012, 17:30
IT Building

IT Building

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


Mr Thulani Jili (University of Zululand)

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.

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Primary author

Mr Thulani Jili (University of Zululand)


Dr Daniel Wamwangi (University of the Witwatersrand) Prof. Elias Sideras-Haddad (University of the Witwatersrand) Dr Filip Tuomisto (Aalto University) Dr Ouassini Nemraoui (University of Zululand)

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