Calculation of positronium compounds, PsLi, PsF, and PsCl, by second-order variational perturbation method

Correlation, positron ionization, and positronium (Ps) binding energies for the ground state (2,1S) of PsLi, PsF, and PsCl together with the excited state (2,1P) of PsF and PsCl are calculated by the second-order variational perturbation method with partial wave expansion. Estimated positronium binding energies for PsLi(2,1S), PsF(2,1S), PsCl(2,1S), PsF(2,1P), and PsCl(2,1P) are −2.19, 2.24, 1.62, −0.16, and −0.05 eV, respectively. The Ps binding energies of PsF(2,1S) and PsCl(2,1S) are in good agreement with the ones estimated by quantum Monte Carlo calculation and also with experimental ones.