Theoretical study of the HeN2+ 2 dication

The structure and stability of the helio nitrogen molecular dication, HeN2+ 2, is investigated by means of standard quantum chemical methods based on both single-reference and multi-reference formalisms. Sequences of correlation consistent basis sets are employed to establish convergence with respect to the size and the quality of the single-particle basis set. MRCI and CASPT2 calculations are reported for the HeN2+ 2 ground-state ion which is found to be metastable. The barrier for the transition state of the reaction HeN2+ 2→ N+ …NHe+ → N+ + NHe+ is calculated to be 59.5 kcals mol−1. The structure of the transition state NHeN2+ was also determined from calculations using the MRCI and CASPT2 methods.