Positron binding to calcium, a configuration interaction study

The configuration interaction (CI) method is applied to the study of the positron-calcium system. A large basis CI investigation shows that positronic calcium, e + Ca, is stable with a binding energy of 0.220 eV and an annihilation rate of 0.64×10 9 s -1 . The stability of e + Ca suggests that the heavier group II elements could also bind a positron, and positron binding to strontium can be regarded as highly likely. The possibility of experimental detection is discussed.