THE ELECTRONIC GROUND-STATE OF THE NEAR2+ DICATION - A COMPLETE ACTIVE SPACE SCF MULTIREFERENCE CI STUDY

The lowest-lying electronic state of the NeAr2+ dication, X 1SIGMA+, has been investigated using accurate ab initio calculations of the complete active space SCF/multireference Cl 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 NeAr2+ diatomic. Thus. the recently experimentally observed NeAr2+ 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 1SIGMA+ electronic ground state potential is purely repulsive must be in a long-lived excited state.