Finite-element multiconfiguration Hartree-Fock calculations of electron affinities of manganese

Finite-element multiconfiguration Hartree-Fock calculations are reported for the 4s23d5 6Se ground and the 4s13d6 6De and 4s13d54p1 8P0 excited states of Mn, and for the low-lying 4s23d6 5De and 4s13d54p2 9Pe states of the Mn− anion. The 4s23d54p1 7P0 state of Mn− is studied by performing configuration interaction calculations in the 9Pe shells. The 7P0 state is found to be the lowest state of the Mn− anion but unbound with respect to the ground state of Mn. The 5De and 9Pe states are higher in energy but still bound with respect to the first excited state of Mn. The ground state electron affinities are −0.498, −1.416 and −1.880 eV for 7P0, 5De, and 9Pe, respectively.