The B3LYP functional in computational chemistry offers advantages such as good accuracy in predicting molecular properties, versatility in handling different types of chemical systems, and efficiency in computational cost compared to other functionals.
Density functional theory (DFT) geometries, vibrational frequencies, barrier heights, and reaction energies are computed for the first reactive channels of reactions involving the hydrogen atoms with CH3OH and C2H5OH. For both reactions, the density functional BB1K specially fitted to study hydrogen abstraction reactions was able to give barrier heights and reaction enthalpies at 0 K with accuracy close to 1.0 kcal/mol. The B3LYP systematically underestimate the classical barrier heights and predict reasonable values for the geometries and frequencies of CH3OH and C2H5OH. The results show that the studied DFTs have strengths and weaknesses which are somewhat complementary.H3C OH + H3C - OHB.Methyl butanoateD.Ethyl ethanoateH3C OH + CH3CH2OH
If we are talking about the anion ClF4 -, it is square planar. The VSEPR method is not easy to apply here. That's why the answer is not obvious. A DFT quantum calculation, B3LYP/6-31G+(d), gives the square planar structure (D4h) about 2.2 eV (about 220 kJ/mol) lower than the T type structure (C2v).
The molecular geometry and electronic structure of styrene and methyl methacrylate as well as corresponding radicals formed by the addition of a methyl radical to the -carbon of the monomer were determined using the density functional theory at the B3LYP/6-311+G** level. Results were in good agreement with the theoretical and experimental data available in the literature. Full optimized molecular geometry of methyl methacrylate showed the trans form of the molecule. Monomers transformed into corresponding radicals preserved the main structural parameters of substituents whereas bonds between substituents and adjacent radical carbon atoms shortened. It was found that the correlation of the theoretically calculated electronic parameters for monomers and the corresponding radicals with the Q and e parameters from the Alfrey-Price scheme strongly depends on the level of calculations. Application of the higher level of theory including the correlation effect changes the relationship discussed in the literature between energy (EY) of formation of a radical from the monomer, the experimental e parameter, and the Q parameter and monomer/average electronegativity, respectively. The total atomic spin density at the radical carbon atom correlated with the radical parameter P in the Alfrey-Price scheme was computed to be higher for the methoxycarbonyl-1-methyl-ethyl radical when compared with the 1-phenyl-propyl radical. These values are in good agreement with the localization energies and the P values determined from the kinetic measurements for macroradicals ending with styrene and methyl methacrylate monomer units. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3761-3769, 2001