Density functional theory B3LYP method

Studies on the trapping and detrapping transition states of atomic hydrogen in octasilsesquioxane using the density functional theory B3LYP method ... 

Notes CCSD(T) coupled cluster method. BLYP, B3LYP, mPWPW91, and TPSS Various density functional theory-based methods. 

The homolytic bond dissociation energies (BDEs) of phenohc O—H bonds has been the subject of a computational study focusing on substituent effects by ab initio and density functional theory (DFT) methods.6 Consistent overestimation of the BDEs by MP2 and MP4 calculations was associated with spin contamination in the reference UHF wave functions, whilst the DFT calculations (particularly the B3LYP/6-31G level of theory) were relatively unaffected. Ab initio calculations of the photosensitized C—C BDEs of /f-phenethyl ethers has revealed a significant configurational... 

These studies, which employed density functional theory (DFT) methods (B3LYP/LANL2DZ/Gaussian 98) proposed that the reactions of all alkali metal phenoxides with C02 followed a similar ground mechanism that comprised three intermediates and three transition states. In step 1, C02 must first be activated by an alkali metal phenoxide. In the case of the sodium phenoxide [24a], C02 can only attack at the polarized O-Na bond to form a Ph0Na/C02 complex as the first intermediate (structure 4). The calculation definitely rules out a direct C-C bond formation at the aromatic ring. 

Nucleophilic vinylic substitutions of 4//-pyran-4-onc and 2,6-dimethyl-4//-pyran-4-one with a hydroxide ion in aqueous solution were calculated by the density functional theory (B3LYP) and ab initio (MP2) methods using the 6-31+G(d) and 6-31G (d) basis sets. The aqueous solution was modelled by a supermolecular approach, where 11 water molecules were involved in the reaction system. The calculations confirmed a different addition-elimination mechanism of the reaction compared with that in the gas phase or non-polar solution. Addition of OH- at the C(2) vinylic carbon of the pyranone ring with an activation barrier of 10-11 kcalmol-1 (B3LYP) has been identified as the rate-determining step, in good quantitative and qualitative agreement with experimental kinetics. Solvent effects increase the activation barrier of the addition step and, conversely, decrease the barrier of the elimination step.138... 

Theoretical methods used for the calculation of BDE and RSE values in recent studies can be divided into two larger groups. The first corresponds to the class of density functional theory (DFT) methods. The most commonly used functional is the B3LYP... 

Theoretical calculations by Siegbahn and Crabtree [4] found the barrier for the reaction via the [PP (R)(H)] intermediate to be a little lower in energy compared with a one-step mechanism, while a study by Hill and Puddephatt favors type interactions [5]. The most recent theoretical study was conducted by Hush and co-workers using density functional theory (B3LYP functional) calculations with double-f to polarized double- basis sets [6]. They also studied solvation effects by a dielectric continuum method. 

Two levels of theory are commonly used in the design of the nickel-based catalysts shown in Figure 11 Density Functional Theory (B3LYP functional used with effective core potentials for Ni and 6-3IG for everything else in the complex) and molecular mechanics (both the UFF (4) and reaction force field, RFF (85,86) are used) (87). All these methods are complementary, and the experiments are guided from the results of several calculations using different molecular modeling techniques. 

Ab initio (HF, MP2, and MP4) (99JCS(P2)801) and SCF + MBTP(2) methods (90JPC7406) also predict the predominance of the thiol tautomer in the gas phase however, the relative stability of the thiol tautomer is overestimated by 1 kcal/mol and 6.5 kcal/mol, respectively. Similarly, calculations using large (TZV2P) basis sets and electron correlation at the QCISD(T) level overestimate the thiol stability by 3.6 kcal/mol (93JCS(P2)861). In contrast, the density functional theory (B3LYP)... 

A significant series of benzo[l,2,4]triazinyls, so-called Blatter s radicals 18 was prepared and their further functionalization was reported. The radicals were characterized by electron paramagnetic resonance (EPR) and electronic absorption spectroscopy, and the results were analyzed in tandem with density functional theory computational methods. In addition, the mechanism for formation of the l,4-dihydrobenzo[l,2,4]triazine ring was investigated using the B3LYP/6-31G(2d,p) method. The formation of the... 

We will always need to employ methods that can account for the electronic structure of our chosen model in some sense - either (1) totally explicitly by ab initio (Hartree-Fock (HF), MpUer-Plesset perturbation theory (MPx), coupled-cluster (CC), etc.) or by density functional theory (DFT) methods with a vast range, and continuously expanding number, of different functionals (B3LYP, M06, etc.), (2) partly explicitly like in semi-empirical (SE) methods (MNDO, AMI, PMx, etc.), or (3) we can even resort to a parameterization such as in classical MD simulations (being a much less prominent method though). All these are of course standard computational methods with generality across any elements and chemistry (for classical MD only if a proper parameter set exists). There is also ab initio MD (AIMD) emerging as a tool in the field. 

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