## Abstract

The trapping rate of positrons into small vacancy clusters and light substitutional impurities in metals is calculated. The host metal is modelled by a uniform jellium with a spherical cavity describing the vacancy of the vacancy cluster. In the case of a substitutional impurity a point charge is placed at the centre of the vacancy cavity. Self-consistent electron densities are solved in the local density approximation for exchange and correlation. The corresponding localised (trapped) and delocalized positron states are calculated using a local form for the electron-positron correlation. The trapping rate is calculated as a function of the initial positron energy and for thermalized positrons as a function of temperature. The model predicts that due to scattering resonances the thermal trapping rate for some small vacancy clusters may exceed that for a single vacancy by more than an order of magnitude. The effect of light impurities H and He is seen to be rather small. The calculations show that the trapping rate is a quantity sensitive to the details of the trapping potential and predict that the experimentally observed trapping rates and their temperature dependence can be very different in different materials.

Original language | English |
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Pages (from-to) | 2235-2248 |

Number of pages | 14 |

Journal | Journal of Physics F: Metal Physics |

Volume | 17 |

Issue number | 11 |

DOIs | |

Publication status | Published - 1987 |

MoE publication type | A1 Journal article-refereed |