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 similar to 0.02 eV. (c) 2008 Elsevier B. V. All rights reserved.