Ground and excited states of the Ne-3(+) molecule

Quantum-chemical ab initio calculations were performed for the electronic g round state and several low-lying excited states of the Ne-3(+) molecular i on. Large parts of the potential energy surfaces, including the global mini mum of the ground state, were treated by means of multi-reference many-body perturbation theory, starting from the SCF wave function of neutral Ne-3. For the inductive local minima of the ground state at C-infinity v and C-2v geometries, the multiconfiguration coupled electron-pair approach was used , together with an extended basis set. In agreement with the best previous calculations, we obtain a symmetric linear (D-infinity h) equilibrium geome try for the Ne-3(+) ground state, with a bond distance of 3.55 a.u. and a b inding energy of 0.10 eV relative to Ne-2(+) and Ne. In addition to this gl obal minimum, two local minima exist, which correspond to a Ne-2(+) ion in its electronic ground state (R-e = 3.27 a.u.) binding a Ne atom by inductiv e forces. Both these minima are very shallow (0.07 and 0.03 eV for the C-in finity v and C-2v structures). Potential energy surfaces for several low-ly ing excited states of Ne-3(+) were calculated as well and their properties, e.g. adiabatic and vertical excitation energies, local minima, and dissoci ation channels, are discussed. (C) 2000 Elsevier Science B.V. All rights re served.