title: Assessing How Correlated Molecular Orbital Calculations Can Perform versus Kohn-Sham DFT: Barrier Heights/Isomerizations.
abstract: To assess the title issue, 38 hydrogen transfer barrier heights and 38 non-hydrogen transfer barrier heights/isomerizations extracted from extensive databases have been considered, in addition to 4 2 p-isomerization reactions and 6 others for large organic molecules. All Kohn-Sham DFT calculations have employed the popular M06-2X functional, whereas the correlated molecular orbital (MO)-based ones are from single-reference MP2 and CCSD(T) methods. They have all utilized the same basis sets, with raw MO energies subsequently extrapolated to the complete basis set limit without additional cost. MP2 calculations are found to be as cost-effective as DFT ones and often slightly more, while showing a satisfactory accuracy when compared with the reference data. Although the focus is on barrier heights, the results may bear broader implications, in that one may see successes and difficulties of DFT when compared with traditional MO theories for the same data.
authors.affiliation: Departamento de Química, and Centro de Química, Universidade de Coimbra, 3004-535, Coimbra, Portugal.
authors.forename: António J C
authors.initials: AJC
authors.lastname: Varandas
authors.affiliation: Departamento de Química, and Centro de Química, Universidade de Coimbra, 3004-535, Coimbra, Portugal.|Universidad de La Habana, Facultad de Química, calle San Lázaro sn., 10400, La Habana, Cuba.
authors.forename: Marco
authors.initials: M
authors.lastname: Martínez González
authors.affiliation: Universidad de La Habana, Facultad de Química, calle San Lázaro sn., 10400, La Habana, Cuba.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Montero-Cabrera
authors.affiliation: Departamento de Química, and Centro de Química, Universidade de Coimbra, 3004-535, Coimbra, Portugal.|Departamento de Química Física Aplicada, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Garcia de la Vega
keywords: ab initio calculations; computational chemistry; density functional calculations; hydrogen transfer; isomerization