The Electronic States of Ni2 and Ni2+

Extensive generalized valence bond (GVB) and configuration interaction calculations (POL-CI) have been carried out for the lowest states of Ni2 and Ni2+ for bond lengths from 1.6 to 4.0 Å. The six lowest states of Ni2 are found to be essentially degenerate with an average equilibrium bond length [FORMULA OMMITED] ground state is found for the ion with a bond length Re =1.96 Å and dissociation energy De=4.14 eV. The bonding of Ni is dominated by the interactions of the 4s orbitals on each Ni with each Ni of Ni2 corresponding to a (4s)1(3d)9 configuration. The lowest states lead to singly occupied 5 orbitals on each center with other 3d occupations leading to 100 electronic states within about 1.0 eV of the ground state.