Reaction path analysis

Although Eq. 27 appears to be the most likely initiation reaction, we cannot rule out a process in which water vapor and DMTC react, based on the ab initio results described in Sect. 4.6. If this does occur, however, it apparently does not lead to homogeneous nucleation of particles, since anecdotal evidence from the glass industry indicates that DMTC and water vapor can be premixed prior APCVD of tin oxide without substantial buildup of solids in delivery lines. Perhaps this is due to significant kinetic barriers to the decomposition of the tin-water complexes that initially form, so that further gas-phase reaction does not occur until the reactants enter the heated boundary layer above the substrate. 

two straightforward reactions lead directly to the thermodynamically most stable tin compound at deposition temperatures, SnCl2. Both Eq. 27 and Eq. 28 produce methyl radicals that can also react with DMTC, as given by Giunta et al.  

Extraction of atoms or groups other than H by CH3 is not expected to be ki-netically favorable. The DMTC radical, Cl2Sn(CH3)CH2, formed in Eq. 29 has relatively strong bonds to carbon  

The oxidation of the methyl radicals formed by DMTC pyrolysis is well understood compared with the tin chemistry. Gas-phase mechanisms describing this chemistry are readily available [61-63]. These reactions lead to the formation of other reactive species that can attack DMTC, including H, O, OH, and HO2. The OH radical in particiflar is a very efficient H-abstractor, and will therefore quickly react with DMTC  

The radical Cl2Sn(CH3)CH2 can react with oxygen via Eqs. 33-35, which are all quite exothermic, supporting Giimta et al. s model in which Cl2Sn(CH3)CH2 is are the principal chain carrier. 

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Molecular mechanics calculations are an attempt to understand the physical properties of molecular systems based upon an assumed knowledge of the way in which the energy of such systems varies as a function of the coordinates of the component atoms. While this term is most closely associated with the conformational energy analyses of small organic molecules pioneered by Allinger (1), in their more general applications molecular mechanics calculations include energy minimization studies, normal mode calculations, molecular dynamics (MD) and Monte Carlo simulations, reaction path analysis, and a number of related techniques (2). Molecular mechanics... 

Figure 26.46 shows the corresponding NOj species vs. the inlet fuel concentration. As the inlet fuel concentration increases, the NO and NO2 emissions increase up to the stoichiometric point. Reaction path analysis shows that the activated reactions of the thermal NOj, mechanism dominate the formation of NO, and NO2 is produced from NO. 

In summary, these results portrayed an intermediate situation where the PT is coupled to the Sn2 geometry change and charge shifting features. It should now be apparent that a study limited to the RC and the TS and lacking a reaction path analysis would have missed most ofthe important mechanistic features discussed herein. 

S. P. Shah and S. A. Rice. Controlling quantum wavepacket motion in reduced-dimensional spaces reaction path analysis in optimal control of HCN isomerization. Faraday Trans., 113 319-331(1999). 

The skeletal or short mechanism is a minimum subset of the full mechanism. All species and reactions that do not contribute significantly to the modeling predictions are identified and removed from the reaction mechanism. The screening for redundant species and reactions can be done through a combination of reaction path analysis and sensitivity analysis. The reaction path analysis identifies the species and reactions that contribute significantly to the formation and consumption of reactants, intermediates, and products. The sensitivity analysis identifies the bottlenecks in the process, namely reactions that are rate limiting for the chemical conversion. The skeletal mechanism is the result of a trade-off between model complexity and model accuracy and range of applicability. 

Through modeling of global experiments it is possible to elucidate the mechanism and identify a number of rate coefficients that must be determined accurately. In this procedure sensitivity and reaction path analyses are essential tools. The sensitivity analysis identifies the bottlenecks in the chemical conversion process, that is the rate-controlling elementary reactions. Reaction path analysis provides information about the major reaction pathways responsible for the production and consumption of each species. 

Suppose the reactive polyatomic molecule of interest can undergo uni-molecular reaction to form several products, and we imagine carrying out a constrained reaction path analysis for each of the product channels. To carry out the analysis of a particular constrained reaction path, Zhao and Rice adopted a system-bath model [74] in which the reaction path coordinate delines the system and all other coordinates constitute the bath. The use of this representation permits the elimination of the bath coordinates, which then increases the efficiency of calculation of the optimal control field for motion along the reaction coordinate. 

Table XXIII displays the rate constants obtained from the MRRKM theory and the reaction path analysis. It is seen that the former are about a factor of two smaller, and the latter about a factor of two larger, than those derived from direct trajectory calculations. We infer that, since both the RRKM and the MRRKM calculated rate constants are smaller than that calculated from trajectory calculations, there is a nonstatistical contribution to the isomerization rate that is not captured by the MRRKM theory.

A reaction path analysis reveals both similarities and differences in the modeling of the formation and destruction chemistry of the CH and CN... 

The results from Findemann s 8 and the configuration entropy show that the melting of Ar7 occurs around 15 K. However, the conventional reaction path analysis failed to monitor the correct onset of the melting. From the reaction path... 

Fig. 10 Reaction path analysis for NO dissociation over a model Cu(l 11) cluster.

Fig. 12. The P-H elimination reaction path analysis for ethyl on Pd(l 11). DFT predicted A) adsorpuon-, H) transition-, and C) product-states.

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