Large-dimension configuration-interaction calculations of positron binding to the group-II atoms

The configuration-interaction (CI) method is applied to the calculation of the structures of a number of positron binding systems, including e⁺Be, e⁺Mg, e⁺Ca, and e⁺Sr. These calculations were carried out in orbital spaces containing about 200 electron and 200 positron orbitals up to =12. Despite the very large dimensions, the binding energy and annihilation rate converge slowly with , and the final values do contain an appreciable correction obtained by extrapolating the calculation to the →∞ limit. The binding energies were 0.00317 hartree for e⁺Be, 0.0170 hartree for e⁺Mg, 0.0189 hartree for e⁺Ca, and 0.0131 hartree for e⁺Sr.