The electronic ground state of the NeAr 2+ dication. A complete active space SCF/multi-reference CI study

Abstract

The lowest-lying electronic state of the NeAr 2+ dication, X 1Σ +, has been investigated using accurate ab initio calculations of the complete active space SCF/multireference CI type employing large one-electron basis sets. A rather deep local minimum is found in the potential energy curve with a barrier of 0.81 eV preventing spontaneous dissociation into the Ne + ( 2P) + Ar + ( 2P) separated atom limit, which is 4.46 eV more stable than the metastable NeAr 2+ diatomic. Thus, the recently experimetally observed NeAr 2+ dication is most probably the ground state ion. This is in sharp contrast to Ne 2+ 2, which is also experimentally known, but since its X 1Σ + electronic ground state potential is purely repulsive must be in a long-lived excited state.