“…The positronium negative ion, e + e − e − , has been investigated by many researchers, not only with the pure Coulomb interactions but with the screened Coulomb potentials as well. Table 4 presents comparison of present ground-state energies and the ones of Saha et al [8], Bhattacharyya et al [17], Ghoshal and Ho [15], Kar and Ho [10], Frolov and Yeremin [1], Frolov and Bishop [2], Drake et al [7], Flores-Riveros and Rivas-Silva [5], and Dutta et al [24] for λ 0. Our results are the best for the strong and medium screening, λ 0.15 au.…”