Tests of second-generation and third-generation density functionals for thermochemical kineticsElectronic supplementary information (ESI) available: Mean errors for pure and hybrid DFT methods. See http://www.rsc.org/suppdata/cp/b3/b316260e/

Abstract

We report tests of second-and third-generation density functionals, for pure density functional theory (DFT) and hybrid DFT, against the BH6 representative barrier height database and the AE6 representative atomization energy database, with augmented, polarized double and triple zeta basis sets. The pure DFT methods tested are G96LYP, BB95, PBE, mPWPW91, VSXC, HCTH, OLYP, and OPW91 and the hybrid DFT methods tested are B1B95, PBE0, mPW1PW91, B97-1, B98, MPW1K, B97-2, and O3LYP. The performance of these methods is tested against each other as well as against firstgeneration methods (BP86, BLYP, PW91, B3PW91, and B3LYP). We conclude that the overall performance of the second-generation DFT methods is considerably better than the first-generation methods. The MPW1K method is very good for barrier height calculations, and none of the pure DFT methods outperforms any of the hybrid DFT methods for kinetics. The B1B95, VSXC, B98, OLYP and O3LYP methods perform best for atomization energies. Using a mean mean unsigned error criterion (MMUE) that involves two sizes of basis sets (both with polarization and diffuse functions) and averages mean unsigned errors in barrier heights and in atomization energy per bond, we find that VSXC has the best performance among pure functionals, and B97-2, MPW1K, and B1B95 have the best performance of all hybrid functionals tested.y Electronic supplementary information (ESI) available: Mean errors for pure and hybrid DFT methods. See

DFT RX3LYP and RPBEPBE studies on the structural, electronic, and vibrational properties of some amino-alcohol ligands

“…These two functionals were employed in conjunction with three basis sets, 6-31G(d,p), 6-31+G(d,p) and 6-311++G(d,p), to investigate the equilibrium bond lengths and valence bond angles, the topology of the electron density and the vibrational properties of the three amino-alcohol ligands, BHEEN, Cyp 2 -EN, and Cy 2 -EN (Scheme 1). It is known that both standard and hybrid exchange-correlation functionals can be used for modeling the structures and properties of chemical systems with acceptable accuracy [30][31][32][33][34] and the B3LYP hybrid functional is one of the many such functionals which has been extensively applied. It has been suggested, however, that the B3LYP functional is inadequate for the description of weak interactions in chemical systems (and this is what we expected to be present in our ligands) because of the lack of electron-electron correlation [35][36][37].…”

Halogen-abstraction reactions from chloromethane and bromomethane molecules by alkaline-earth monocations

“…A search for the stationary points involved in these reactions has been performed, at the Density Functional Theory (DFT) level, using the mPW1K 19 functional in conjunction with the QZVPP Ahlrichs's basis sets. 21 In addition, kinetics calculations have been accomplished in the framework of the conventional/variational microcanonical transition state theory.…”

“…In particular, we have chosen the second-generation modifiedWang-1-parameter method for the kinetics (mPW1K) functional, 18 which has previously proved its ability to describe the PESs of reactions between analogous systems and gives accurate barrier heights. 19 This functional is based on a modified version of the Perdew-Wang gradient-corrected exchange functional by Adamo and Barone 20 and the Perdew-Wang gradient-corrected correlation functional. Regarding basis sets, we have employed Ahlrichs' quadruple-z quality (QZVPP) basis sets.…”

Understanding Enzyme Catalysis Using Computer Simulation

“…For currently used hybrid DFT functionals, geometries are generally quite accurate, and energetic errors are typically in the range of 3-5 kcal/mol. [45][46][47] Thus, results are often of sufficient accuracy to distinguish between likely and unlikely mechanisms and to assist in interpreting experimental data. One method for ensuring the convergence of results with respect to system size in quantum chemical cluster calculations is known as "accretion", 26,31,35,48 which involves systematically increasing the number of atoms in the cluster until PCM solvation corrections no longer significantly affect the result.…”