Theoretical evidence of bound metastable states in the doubly ionized nickel dimer Ni-2(2+)

Density functional theory (DFT) with generalized gradient corrections is us ed to study the electronic structure of Ni-2(2+). We predict several bound metastable states, all of them having four unpaired electrons. Those states are stabilized against dissociation by a Coulomb barrier. The stability ca n be explained as due mainly to the interaction between the s electrons of the constituent Ni+ cations, with d(8)s(1) configurations, that pair themse lves in a bonding sigma molecular orbital. (C) 2000 Elsevier Science B.V. A ll rights reserved.