title: Quantum chemical assessment of the binding energy of CuO+.
abstract: We present a detailed theoretical investigation on the dissociation energy of CuO(+), carried out by means of coupled cluster theory, the multireference averaged coupled pair functional (MR-ACPF) approach, diffusion quantum Monte Carlo (DMC), and density functional theory (DFT). At the respective extrapolated basis set limits, most post-Hartree-Fock approaches agree within a narrow error margin on a D(e) value of 26.0 kcal mol(-1) [coupled-cluster singles and doubles level augmented by perturbative triples corrections, CCSD(T)], 25.8 kcal mol(-1) (CCSDTQ via the high accuracy extrapolated ab initio thermochemistry protocol), and 25.6 kcal mol(-1) (DMC), which is encouraging in view of the disaccording data published thus far. The configuration-interaction based MR-ACPF expansion, which includes single and double excitations only, gives a slightly lower value of 24.1 kcal mol(-1), indicating that large basis sets and triple excitation patterns are necessary ingredients for a quantitative assessment. Our best estimate for D(0) at the CCSD(T) level is 25.3 kcal mol(-1), which is somewhat lower than the latest experimental value (D(0) = 31.1 ± 2.8 kcal mol(-1)[semicolon] reported by the Armentrout group) [Int. J. Mass Spectrom. 182/183, 99 (1999)]. These highly correlated methods are, however, computationally very demanding, and the results are therefore supplemented with those of more affordable DFT calculations. If used in combination with moderately-sized basis sets, the M05 and M06 hybrid functionals turn out to be promising candidates for studies on much larger systems containing a [CuO](+) core.
authors.affiliation: Institut für Anorganische und Analytische Chemie, Johann Wolfgang Goethe-Universität Frankfurt, D-60438 Frankfurt am Main, Germany.
authors.forename: Elixabete
authors.initials: E
authors.lastname: Rezabal
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gauss
authors.forename: Jon M
authors.initials: JM
authors.lastname: Matxain
authors.forename: Robert
authors.initials: R
authors.lastname: Berger
authors.forename: Martin
authors.initials: M
authors.lastname: Diefenbach
authors.forename: Max C
authors.initials: MC
authors.lastname: Holthausen
mesh_terms: D003300:Copper / Q000737:chemistry*; D009010:Monte Carlo Method; D011789:Quantum Theory
chemical_list: D003300:Copper; C000520:cuprous oxide