Positron annihilation from F centers of alkali halide crystals

Kanhere, D. G. ; Farazdel, Abbas ; Smith Jr., Vedene H. (1987) Positron annihilation from F centers of alkali halide crystals Physical Review B, 35 (7). pp. 3131-3137. ISSN 0163-1829

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Official URL: http://prb.aps.org/abstract/PRB/v35/i7/p3131_1

Related URL: http://dx.doi.org/10.1103/PhysRevB.35.3131


Two-photon annihilation of a positron from an F center in an alkali halide crystal has been studied theoretically by accurately solving with the integral transform (generator coordinate method) the two-particle (electron-positron) problem for two different model crystal potentials (an effective Coulomb potential and the Krumhansl-Schwarz cavity potential) which are often used in the theoretical description of F centers. Calculations are presented of the stability and relevant expectation values of the positron-F-center system, the two-photon annihilation lifetime τ and the angular correlation distribution N(theta) for sixteen different alkali halides. Comparison is made with available experimental data and previous, less accurate calculations. It is demonstrated that a proper description of electron-positron correlation in the wave function is necessary in order to obtain meaningful results. We have also established a range of effective charges, Z, of the defect that can capture an electron-positron pair in a stable state. For the Krumhansl-Schwarz potential, the present highly accurate calculations show that all sixteen crystals have stable electron-positron states in the defect.

Item Type:Article
Source:Copyright of this article belongs to American Physical Society.
ID Code:16262
Deposited On:15 Nov 2010 13:57
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