The stability of the ground state for positronic sodium

The existence of a stable ground state for the exotic NaeC atom is demonstrated by using a modified version of the stochastic variational method to solve the Schr¨odinger 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 NaC core at distances of the order of 10–30 a0. It is found that positronic sodium is stable against decay into Ps C NaC with a binding energy of 0.000 177 Hartree