A new, more accurate calculation of the ground-state wave function of positronium hydride has been carried out. The method is variational and is similar to that reported by Lebeda and Schrader. The "molecule" is found to be stable against separation into positronium and hydrogen by at least 0.672 eV, an increase of 2% above the best previous value. The mean lifetime against two-photon annihilation is 0.407 nsec, as obtained from the energy-minimizing wave function. The "cusp value" of -0.477 is close to the exact value -½, giving an indication of the quality of the trial function.

• Received 20 September 1972

DOI:https://doi.org/10.1103/PhysRevA.7.819