Bond dissociation energy computation

Even within a particular approximation, total energy values relative to the method s zero of energy are often very inaccurate. It is quite common to find that this inaccuracy is almost always the result of systematic error. As such, the most accurate values are often relative energies obtained by subtracting total energies from separate calculations. This is why the difference in energy between conformers and bond dissociation energies can be computed extremely accurately. 

AH and AS to various notional subprocesses such as bond dissociation energies, ionization energies, electron affinities, heats and entropies of hydration, etc., which themselves have empirically observed values that are difficult to compute ab initio. 

Table 2. Bond dissociation energies D [kcal mol 1] at the computational level MP2/6-31G //HF/6-31G + ZPE bond lengths R [A] and wave numbers v [cm 1] of the stretching modes (HF/6-31G ).

Table 4. Bond dissociation energies D [kcal mol 1] at the computational level MP2/6-31G //HF/6-31G + ZPE.

In an alternative assessment of the effectiveness of these computer programs, it was concluded that explosive power was over-emphasised in relation to the more practically important aspect of sensitivity to initiation, and many compounds were being indicated as hazardous when they were not. There was also no provision for considering polymerisation as a hazardous possibility, and there was little quantitative data on this. The parameter best correlating with material sensitivity is the bond-dissociation energy. It was recommended that regulations specifying the... 

As stated above, the thermochemistry of free radicals can also be estimated by the group additivity method, if group values are available. With the exception of a few cases reported in Benson (1976), however, such information presently does not exist. Therefore, we rely on the model compound approach (for S and Cp) and bond dissociation energy (BDE) considerations and computational quantum mechanics for the determination of the heats of formation of radicals. 

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... 

Bond dissociation energies (BDEs) are at the heart of organic thermochemistry and many mechanistic considerations, so it is imperative to be able to compute and predict these quantities accurately. The problem is that, upon lengthening a bond in the early stages of cleaving... 

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