Does N-2(-) exist? A coupled-cluster study

Potential energy curves of the ground-state N-2 molecule and its doublet N- 2(-) anion are calculated at the coupled-cluster level with single and doub le excitations and with noniterative triples [CCSD(T)] as well as with the multireference averaged-quadratic coupled-cluster (MR-AQCC) method. The N-2 (-) anion is shown to be temporary and decays to its neutral parent plus a free electron at bond lengths shorter than approximate to 1.4 and larger th an approximate to 2.5 Angstrom. Thus, the N-2(-) anion exists within the 1. 4 less than or equal to R (N-N) less than or equal to 2.5 Angstrom range at the Born-Oppenheimer approximation. (C) 1999 American Institute of Physics . [S0021-9606(99)00511-5].