Multiple decomposition channels

Multiple decomposition pathways observed Possible reaction channels of the enol ion in 1029... 

It is well-known that such functions can suffer from large amounts of spin contamination and are not suited to obtaining any surfaces except those that are the lowest of a given S3niraietry. However the UHF function, unlike an RHF function, will usually allow a molecule to separate correctly into its fragments for all decomposition channels. In contrast multi-reference-function techniques that include all configurations required to achieve correct separation would be intractable for even most three- and four-atom molecules. To limit the uncertainty introduced in using a UHF function for open shells, we monitor the multiplicity in the calculations. For some cases, such as the A A" state of HNO in the present paper, it offers a caution on the interpretation of the results, while for other cases, such as the A HCO surface, no multiplicity problems are encountered. 

In 2009, Xu et al. completed a comprehensive study of the C2H5O potential energy surface, reporting on the decomposition and isomerization reactions of all three C2H5O radicals and reviewing the previous hterature. Multiple decomposition paths were found for all species, with a main channel accounting for >75% of reaction for each species at moderate to h h pressures and temperatures below about 800 K the secondary processes were predicted to increase in importance at higher temperatures and lower... 

An opposite situation is found for the catalytic N O decomposition over Fe/ZSM-5 [46]. Although mononuclear Fe sites are highly active for the dissociation of the first N O molecule, further catalytic reaction is hampered in this case by a very high barrier for the activation of the second N O molecule necessary for the formation and completion of the catalytic cycle. The binuclear [Fe(p-0)2Fe] + and [Fe(p-0)Fe] + complexes are much more catalytically active. Each iron center in such complexes acts as an independent Np dissociation center. This allows the formation of two proximate labile extra-framework O species, which easily recombine to form molecular O. The reaction mechanism in this case is highly complex (Fig. 9). It involves multiple changes in the spin-state of the iron complexes as well as the interconversion between the [Fe(p-0)2Fe] and [Fe(p-0)Fe] active complexes in the course of the catalytic process. The identification of the preferred reaction channel based only on the results of DFT calculations is not possible. 

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