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Abstract: Accurate double ionization energies (DIEs) for low-lying doubly charged states of HCl, HBr, Cl2 and Br2 were calculated using non-relativistic CASSCF/MRCI level of theory with the aug-cc-pVQZ basis set. The results are in excellent agreement with experimental data, presenting absolute average deviations lower than 0.3eV. Some DIEs not previously assigned or well characterized are discussed. Further improvements can be reached by including relativistic effects. [Copyright &y& Elsevier]

Abstract: Geometries, energies, frequencies, and rate constants of the reaction F (2P)+C2H6 →C2H5 +HF were computed using the MP2 and CCSD(T) approaches, correlation-consistent basis sets, and an extrapolation scheme to assess the complete basis set (CBS) limit energies. Values of the enthalpy of reaction at 0K calculated with the CCSD(T)/cc-pVQZ method and extrapolated to the CBS limit are equal to −35.2 and −36.7kcal/mol, respectively (Exp. −35.3±0.5kcal/mol). Rate constants calculated with the zero-order interpolated variational transition state (IVTST-0) method are in good agreement with experiment. [Copyright &y& Elsevier]

Abstract: Kinetic isotope effects (KIE) for hydrogen abstraction from CH4, CD4, and 13CH4 by fluorine was studied by the variational transition state theory with multidimensional tunneling contributions (VTST/MT). A low-level potential energy surface is obtained with the AM1SRP method. High-level energies, geometries and frequencies of the reactants, transition state, and products were computed using MP2 and CCSD(T) methods. Using the CVT/μOMT method, the kH/kD kinetic isotope effect value is 1.52 (298K), in excellent agreement with experimental values (1.4–1.5). All computed values of k12C/k13C KIE over a large range of temperatures (200–2000K) show normal values (KIE>1). [Copyright &y& Elsevier]

Abstract: Barrier heights, structures, reaction energies, and rate constants are calculated with the DFT, MP2, and CCSD(T) methods for the first two channels of the H+CH3OH reactions. The best estimate results based on CCSD(T) calculations give reaction enthalpies () for the first (−8.4kcal/mol) and second (0.8kcal/mol) reactive channels, which are comparable to the experimental values, −8.8±0.9 and −0.3±0.9kcal/mol, respectively. Rate constants and activation energies calculated with the IVTST-0 method using CCSD(T)/cc-pVTZ geometries and frequencies are also in excellent agreement with experiment data. [Copyright &y& Elsevier]

Abstract: Geometries, frequencies, energies, and rate constants of the reaction N(4S)+CH4 →NH+CH3 were computed using coupled-cluster theory, correlation-consistent basis sets, and extrapolations schemes to assess the complete basis set limit energies. Our best calculation gives a classical barrier height and reaction energy of 32.9 and 29.3kcal/mol, respectively, and 24.6kcal/mol for the reaction enthalpy (. Thermal (200–2000K) rate constants were calculated with the canonical variational transition state theory, and indicate a very slow reaction when compared with the ones with N(2D) and N(2P). Using the CVT/μOMT method, the value of H/D KIE is 6.3 (300K). [Copyright &y& Elsevier]

Accurate potential energy curves, dissociation energies, and molecular constants for several low-lying singlet and triplet electronic states of AsCl were investigated using the CASSCF/MRCI methodology, including the spin–orbit splitting with the aug-cc-pV5Z-DK basis set. Our results represent an improvement over previous the theoretical descriptions for the lowest lying states, as well as characterize another higher excited state not previously investigated. Transition probabilities and radiative lifetimes for the (1) 3 Π → X 3 Σ − band system were also predicted using Einstein spontaneous emission coefficients. [ABSTRACT FROM AUTHOR]

Highlights: [•] Accurate structures of aluminum clusters: Al n x (n =1–9, x =0, ±1). [•] Electron affinities and ionization potential. [•] DFT and CCSD(T) electronic calculations. [ABSTRACT FROM AUTHOR]

Accurate potential energy curves, transition moments, spectroscopic constants, radiative transition probabilities, and lifetimes for the states X 3Σ-, (1) 3Π, and (2) 3Σ- of BeC, MgC, and CaC are reported using high level calculations. Diagonal transitions dominate for the (2) 3Σ- → X 3Σ- system, with band origins falling at 745, 648, and 770 nm, and an intensity ratio of 6,3,1, respectively for BeC, MgC, and CaC. Radiative lifetimes for v′=0 are equal to 0.48, 1.45, and 3.29 μs for the state (2) 3Σ-, and equal to 13.57, 10.44, and 9.62 μs for the state (1) 3Π for BeC, MgC, and CaC. [Copyright &y& Elsevier]