Effect of electron-electron correlations on positron-electron momentum density distributions

The calculations of the influence of the self-energy effects on the electron-positron (e-p) enhancement factors and the e-p momentum distributions are presented. The approach bases on the novel formulation of the Bethe-Goldstone (B-G) equation for the positron in an electron gas where the scattering of the electrons into the states below the Fermi surface due to the self-energy effects is allowed. This equation has been solved and the corresponding e-p enhancement factors and momentum distributions have been found. The agreement between the absolute values of the theoretical calculations and experimental data has improved noticeably. (author)