O + H2 reaction

Figure 8. The effect of rotational excitation on the distribution of collisions at the barrier for O + H2 reaction, for j = 0 ( ) and for j = 10 (o). The collision energy was 0 = 12 kcal/mol in each case[61].

The hyperspherical and related coordinates which have been considered in this work have served for the visualization of critical features of potential energy surfaces [91,92], crucial for the understanding of reactivity (role of the ridge [93] and the kinetic paths [94]). In [95], the PES for the O + H2 reaction was studied. A discrete hyperspherical harmonics representation is presented in [96] for proton transfer in malonaldehyde. 

In the kinematic mass model investigation of the strong j dependence of the reaction cross-section in the O + H2 reaction [61] the shape of the critical dividing surface in the region relevant for the reaction was approximated by an ellipsoid with the axes a =... 

We discussed the implications of the O + H2 reaction s multiple bottleneck regions in terms of variational and supernumerary transition states. We related the observed features to the scattering results for asymmetrical Eckart potentials. We emphasized that global control is maintained to very high energy (1.9 eV) and very high levels of v2. We demonstrated the influence of quantized transition states at the level of state-selected reaction probability for this reaction. 

Figure 6 Oxygen isotope distribution during C O + H2 reaction at 423 K over RI1CI3 + MnCl2/Si02 catalyst (P° = 170 torr, H2/CO s 2, C 0 99%, 1.0 g catalyst) (reproduced from Reference 38).

Recently we have studied the O+H2 reaction. This reaction proceeds through a deep well and has no bottle neck geometry. It has proved impossible to apply or formulate a J shifting approximation for this case. We have therefore developed a capture model [14]. 

Model Studies of Intersystem Crossing Effects in the O + H2 Reaction... 

This result is reasonably well described by surface hopping within the diabatic representation the corresponding adiabatic representation results are less accurate below the adiabatic threshold, but more accurate above threshold. If the crossing occurs on the product side of the barrier, as actually occurs for the O + H2 reaction, the influence of intersystem crossing is much smaller, though not completely. The influence of Stuckelberg interference effects on the state-resolved reaction probabilities is also studied. 

Recently, Hoffmann and Schatz(7ij have developed a new level of treatment of spin-orbit effects in bimolecular reactions which enables a more sophisticated treatment of intersystem crossing d3mamics than in the past. In this treatment high quality electronic structure n thods are used to determine global surfaces for the reaction and spin-orbit matrix elements, and then trajectory surface hopping (TSH) methods are used to determine properties of the bimolecular collisions such as reactive cross sections and state distribution information. In an application of this theory to the O + H2 reaction, the spin-orbit matrix elements were determined as a function of position, and then TSH calculations were done within a diabatic representation to determine cross sections. Intersystem crossing effects were found to be small for O + H2 due to... 

In this paper, we compare quantum scattering, TSH-A and TSH-D results for several two-state reaction path models which describe the O + H2 reaction, and related reactions. Eleven model potentials have been considered, so as to determine the influence of triplet-singlet crossing location, the singlet well depth, and the size and coordinate dependence of the spin-orbit coupling. 

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