title: Accurate computational determination of the binding energy of the SO3 x H2O complex.
abstract: Reliable thermochemical data for the reaction SO3 + H2O<-->SO3 x H2O (1a) are of crucial importance for an adequate modeling of the homogeneous H2SO4 formation in the atmosphere. We report on high-level quantum chemical calculations to predict the binding energy of the SO3 x H2O complex. The electronic binding energy is accurately computed to De = 40.9+/-1.0 kJ/mol = 9.8+/-0.2 kcal/mol. By using harmonic frequencies from density functional theory calculations (B3LYP/cc-pVTZ and TPSS/def2-TZVP), zero-point and thermal energies were calculated. From these data, we estimate D0 = -Delta H(1a)0(0 K) = 7.7+/-0.5 kcal/mol and Delta H(1a)0(298 K) = -8.3+/-1.0 kcal/mol.
authors.affiliation: Center for Functional Nanostructures (CFN) and Lehrstuhl für Theoretische Chemie, Institut für Physikalische Chemie, Universität Karlsruhe (TH), D-76128 Karlsruhe, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Fliegl
authors.forename: Andreas
authors.initials: A
authors.lastname: Glöss
authors.forename: Oliver
authors.initials: O
authors.lastname: Welz
authors.forename: Matthias
authors.initials: M
authors.lastname: Olzmann
authors.forename: Wim
authors.initials: W
authors.lastname: Klopper