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 gr ound S states (L=0) in these systems and the Ps(2) molecule have been determined by extensive variational calculations. The hyperfine struct ure of these states is also investigated. The positron annihilation ra tes have been evaluated for the positronium hydrides, the Pst molecule , and the Ps(-) ion and compared. The positron annihilation rates Gamm a(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 sy stem) than in the Ps(2) molecule.