Influence of the effective electron-positron correlation potential on the calculation of momentum densities of positron annihilation pairs

In this work we apply the 2C-DFT (two-component density-functional theory) within the Kohn-Sham scheme and the local density approximation in the limit of small positron densities to the determination of the electron and positron states of one positron in the alkali metals lithium, sodium and potassium. For the representation of the electron and positron crystal wave functions we use a numerical-basis-set LCAO (linear combination of atomic orbitals) expansion. Since the positron is assumed to be in the ground state Γ1, ψ+ has the symmetry of the crystal lattice, therefore, we put to use the LSO (localized spherical orbitals) method. As a result we show the influence of the effective electron-positron correlation potential on ψ+ and on the high momentum components of annihilation rates within the IPA (independent particle approximation). (orig.)