Nonlocal effects in the electron-positron interaction in metals - art. no.165115

We study the importance of the nonlocal electron-positron interaction for p ositron annihilation characteristics in simple and transition metals. This is accomplished by using the weighted density approximation, giving rise to nonlocal and energy-dependent electron-positron correlation functions. We apply this formalism to study the momentum-dependent and momentum-averaged electron-positron enhancements of the positron annihilation rates and the t hree-dimensional electron-positron momentum densities. The results of the p resent approach are compared to those obtained within the local density app roximation, generalized gradient approximation, Bloch modified ladder appro ximation, and experimental data. We find that while nonlocality of the elec tron-positron correlations is of substantial importance for the core and d electrons in transition metals, for nearly-free-electron bands the energy d ependence of the electron-positron correlation functions is of more signifi cance.