An extrapolation method for the partial wave energy of positron-atom complexes

An extrapolation method is proposed for the partial wave energy of positron-atom complexes, and its performance is examined. To this end, large-scale configuration interaction (CI) and Hylleraas calculations for complexes of one positron and virtual hydrogenic atom with the nuclear charge Z (Z = 0.5, 0.6, 0.7, and 0.8) were carried out. As a test application for many-electronic complexes, the method is applied to find the CI energy of PsLi, and the binding energy (BE) of positronium and Li atom is calculated. This BE is smaller than more accurate values by only ∼0.02 eV.