Positronium negative ion: An adiabatic study using hyperspherical coordinates

Abstract

We treat the positronium negative ion adiabatically in hyperspherical coordinates. The potential curves of the ground state and of the first ${}_{}{}^1{}_{}{}^{}S$ doubly excited state are calculated variationally. The corresponding energy levels are in good agreement with previous calculations, showing that the approximate separation of the wave function in hyperspherical coordinates has roughly the same validity as in ${\mathrm{H}}^{-}$.