Calculations for the ground states of positronium halides by singly and doubly excited configuration interaction method

Singly and doubly excited configuration interaction calculations for the ground states of positronium halides, PsF, PsCl, PsBr, and PsI, are performed, and positron ionization energies, positronium binding energies, and two-photon annihilation rates are reported. It is shown that the correlation effects increase their values calculated by the Hartree–Fock method. In particular, the increases of the two-photon annihilation rates are very large.