Computational Chemistry

7.2.3.4d Meta-Generalized Gradient Approximation Functionals (meta-GGA, MGGA) We saw that functionals which use the first deriva ...

The percentage of HF exchange energy to use is a main distinguishing characteristic of the various hybrid functionals. The first ...

Jacob’s ladder.” From this it is evident that “fully nonlocal” DFT theory does not promise a single, sharply defined functional, ...

overrated” (relevant to the latter statement he points out that “there are many, many, different ways to tackle the electronic s ...

Levine has compared various properties from DFT with those from molecular mechanics, ab initio, and semiempirical methods [ 66 ] ...

O H H HH Cs C3v 103.7 104.1 103.0 103.9 (104.5) C2v B3LYP / 6-31G* Experiment 0.969 0.964 0.976 0.969 (0.958) MP2(fc) / 6-31G* M ...

Table 7.1 Errors in calculated bond lengths (A ̊) and angles (degrees) for the 20 molecules of Fig.7.1. The errors are calculate ...

Table 7.1 (continued) Molecule B3LYP M06 TPSS MP2 Exp "1.2 "1.6 "1.1 "0.8 A 110.6 Ethene 0.003 0.004 0.005 0.000 L 1.085 2 L, 1 ...

PBE [ 72 ] (a nonempirical GGA functional; Section7.2.3.4c). TPSS [ 73 ] ( a nonempirical meta-GGA functional; Section7.2.3.4d) ...

TPSS was given precedence over PBE because it lies on a higher rung, which does not mean that for every task it will be more acc ...

methods give good bond angles (to within ca. 1; ca. 2for some CH 3 NH 2 angles). For bond lengths positive deviations are very ...

approximately 6-311G-type basis set. These workers found average bond length errors of, e.g., 0.01 A ̊for C–H and 0.009 A ̊for C ...

of saturation where relative energies are concerned; energies are discussed in the next section. The insensitivity of geometries ...

7.3.2 Energies.......................................................... 7.3.2.1 Energies: Preliminaries Usually, we seek from a ...

K enthalpies were calculated by Gaussian 03 [ 78 ] (except for M06, by Spartan ‘08 [ 71 ]) using a statistical mechanics algorit ...

First we note that the high-accuracy (G3(MP2), CBS-QB3, and CBS-APNO; Section 5.5.2.2b) values are close to the reported measure ...

connection method [ 57 ]) gave the best reaction energies [ 74 ]. Many energy differ- ence comparisons have been published compa ...

in several program suites. Ventura et al. found DFT to be better than CCSD(T) (a high-level ab initio method, Section 5.4.3) for ...

In lieu in a full repertoire of experimental results, for a quantitative comparison of the effect on these four reactions of var ...

Table7.7suggests that for these calculations the 6-311+G basis leads to essential saturation, with reaction energies becoming al ...