The stability of the ground state for positronic sodium

The existence of a stable ground state for the exotic Nae(+) atom is demonstrated by using a modified version of the stochastic variational method to solve the Schrodinger equation for a positron and valence electron moving under the influence of a model potential. The model potential consists of the direct interaction between the positronium and the Hartree-Fock wavefunction for the alkali ion. The exchange potential between the valence electron and the core electrons is approximated with a local potential. The structure of positronic sodium is best described as a slightly stretched and polarized positronium atom orbiting the Na+ core at distances of the order of 10-30 a(0). It is found that positronic sodium is stable against decay into Ps + Na+ with a binding energy of 0.000 177 Hartree.