THEORETICAL CALCULATIONS OF POSITRON-ANNIHILATION WITH RARE-GAS CORE ELECTRONS IN SIMPLE AND TRANSITION-METALS

Positron-annihilation rates, momentum densities of positron-annihilation pairs, and electron-positron enhancement factors for rare-gas core electrons in 27 frequently investigated metals are calculated. The sensitivity of these quantities to various parameters of electron and positron models applied-namely, to the electron-electron exchange and correlation potential, electron configuration, lattice dimensions, and the shape of positron wave function, as well as the size of relativistic effects-is studied. The influence of inclusion of electron-positron correlations into both electron and positron wave functions on resulting annihilation characteristics is discussed. It is shown that the present approach reproduces fairly well also the total positron-annihilation rates and positron lifetimes.