Chemical stability of positronic complexes with atoms and atomic ions

A simple theory for establishing the stability or instability of positron-atomic systems against dissociation is presented. The theory consists of assuming that Morse-potential parameters for protonic diatoms are transferrable to the corresponding positronic molecules, and making appropriate reduced-mass modifications in the calculation of binding energies. The surprisingly good reliability of the method is established by appealing to the well-known positronium affinities of atomic hydrogen and fluorine. Positronium (Ps) binding is found for about half of the 42 atoms tested. In addition, instability is indicated for all nine positron-atom systems tested, and stability is indicated for seven of eight negatively charged systems tested; e.g., PsO-