Positronium hydrides and the PS2 molecule: Bound-state properties, positron annihilation rates, and hyperfine structure

The bound-state spectra of the positronium hydrides (infinity)HPs, TPs, DPs, (1)HPs, and MuPs are considered. The properties of the bound ground S states (L=0) in these systems and the Ps(2) molecule have been determined by extensive variational calculations. The hyperfine structure of these states is also investigated. The positron annihilation rates have been evaluated for the positronium hydrides, the Pst molecule, and the Ps(-) ion and compared. The positron annihilation rates Gamma(ny) (where n greater than or equal to 2) in the positronium hydrides are significantly closer to those in the Ps(-) ion (the three-body system) than in the Ps(2) molecule.