The existence of a 2Po excited state for the e+Ca system
  The Configuration Interaction method is used to demonstrate that there is an electronically stable state of positronic calcium with an orbital angular momentum of L=1. This prediction relies on the use of an asymptotic series to estimate the variational limit of the energy. The best estimate of the binding energy is 37 meV. A discussion of the structure of the system is also presented. 
M. W. J. Bromley and J. Mitroy