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Abstract: We discuss and review selected recent applications and validations of the Minnesota density functionals, especially the M06 family, emphasizing nanochemistry, organic, inorganic, and biological chemistry, and catalysis and highlighting the broad accuracy of these functionals as compared to previous popular functionals for thermochemistry, kinetics, and noncovalent interactions. [ABSTRACT FROM AUTHOR]

Abstract: We present benchmark calculations of nine selected points on potential energy surfaces describing proton transfer processes in three model systems, , CH3OH…H+…OH2, and CH3COOH…OH2. The calculated relative energies of these geometries are compared to those calculated by various wave function and density functional methods, including the polarized molecular orbital (PMO) model recently developed in our research group and other semiempirical molecular orbital methods. We found that the SCC-DFTB and PMO methods (the latter available so far only for molecules consisting of only O and H and therefore only for the first of the three model systems) give results that are, on average, within 2kcal/mol of the benchmark results. Other semiempirical molecular orbital methods have mean unsigned errors (MUEs) of 3–8kcal/mol, local density functionals have MUEs in the range 0.7–3.7kcal/mol, and hybrid density functionals have MUEs of only 0.3–1.0kcal/mol, with the best density functional performance obtained by hybrid meta-GGAs, especially M06 and PW6B95. [Copyright &y& Elsevier]

Abstract: The structures of Pd(PH3)2 and Pt(PH3)2 complexes with ethene and conjugated C n H n +2 systems (n =4, 6, 8, and 10) were studied. Their binding energies were calculated using both wave function theory (WFT) and density functional theory (DFT). Previously it was reported that the binding energy of the alkene to the transition metal does not depend strongly on the size of the conjugated C n H n +2 ligand, but that DFT methods systematically underestimate the binding energy more and more significantly as the size of the conjugated system is increased. Our results show that recently developed density functionals predict the binding energy for these systems much more accurately. New benchmark calculations carried out by the coupled cluster method based on Brueckner orbitals with double excitations and a quasiperturbative treatment of connected triple excitations (BCCD(T)) with a very large basis set agree even better with the DFT predictions than do the previous best estimates. The mean unsigned error in absolute and relative binding energies of the alkene ligands to Pd(PH3)2 is 2.5kcal/mol for the ωB97 and M06 density functionals and 2.9kcal/mol for the M06-L functional. Adding molecular mechanical damped dispersion yields even smaller mean unsigned errors: 1.3kcal/mol for the M06-D functional, 1.5kcal/mol for M06-L-D, and 1.8kcal/mol for B97-D and ωB97X-D. The new functionals also lead to improved accuracy for the analogous Pt complexes. These results show that recently developed density functionals may be very useful for studying catalytic systems involving Pd d10 centers and alkenes. [Copyright &y& Elsevier]

Alkylperoxyl (RO 2) and hydroperoxyalkyl (QOOH) species are crucial intermediates produced during the autoignition of transport fuels, and consequently their thermodynamic and kinetic data are very important. Since these data are not available experimentally, we take up the challenge of computing them from first principles. We compare the 1,5 shifts in 2-methyl-4-heptylperoxyl radical and 3-methylcyclohexylperoxy radical to clarify the similarities and differences of the kinetics of chain alkanes and cycloalkanes in the fuel oxidation mechanism. In order to take account of the multistructural and coupled torsional anharmonicity, we employ multistructural canonical variational transition state theory (MS-VTST) with multidimensional tunneling to calculate rate constants. The calculations explicitly include all conformers: 6 and 154 for the two reactants, 7, 6, 1, and 1 for the four transition states, and 289, 282, 8, and 5 for the four products (which are the reactants for the reverse reactions). The effects of various factors on the thermodynamic data and calculated rate constants are evaluated in detail. We found that multistructural torsional anharmonicity has a very large effect on the rate constants. This work illustrates how modern density functional and dynamics methods make it possible to calculate accurate rate constants for both branched-chain and cycloalkane peroxy radicals and hydroperoxy species. [ABSTRACT FROM AUTHOR]