Analysis of the annihilation data in noble metals, Mg and Cd by Mijnarends' method

The momentum density distribution of the annihilating electrons rho(p) along the main crystallographic directions for Cu, Ag, Mg and Cd has been calculated using experimental results obtained for the angular distribution of the annihilation radiation. For Cu, Ag and Au the model momentum distribution functions in the same crystallographic directions have been derived from the expected angular distributions. These distribution functions have been obtained from certain geometric models of the Fermi surface (FS) under the assumption that the density of occupied momentum states is constant. All the distribution functions rho(p) have been calculated by Mijnarends' method. Comparison of the experimental and model results permits us to examine the influence of the deformation of the shape on the functions rho(p) derived by Mijnarends' method. The influence of the number of angular distributions (used in the calculations) on the functions rho(p) has been also examined. For Mg, Zn and Cd the effects of the influence of the lattice periodic potential on the electron-positron interaction has been noticed. (author)