Kinematic mass model

Kinematic mass model can actually be derived for reaetions of two polyatomic molecules, along the lines of reasoning developed in the energy transfer studies [30,31]. This possibility has not been explored yet. In the present case a derivation of the model will be presented for reactions of atoms with polyatomic molecules. The model will be... 

Bc, AB ). They have to be transformed to Jaeobi eoordinates (r R,y) in order to be apphed in the kinematic mass model. 

The reaction 0( P) + H2 OH + H is important in combustion and as a prototypical oxygen atom reaction. A considerable number of theoretical and experimental investigations of this reaction that have been reported are quoted in the trajectory study [63] devoted primarily to the effects of reagent rotation in this reaction. The work in [63] is based on Johnson-Winter LEPS potential surface [64] from which also the relevant parameters were derived for the kinematic mass model analysis [61] of the trajectory results in question. 

Figure 7. Reaction cross sections for O + H2(v = 0, j) as function of j. (o, ), ( , ), and (A, A) correspond to collision energies Etrjns = 20. 15 and 12 kcal/mol respectively. Open symbols quasiclassical trajectory results [64], full symbols results of the kinematic mass model calculations. Effect of reagent rotation on the distribution of collisions at the barrier is neglected in (a) it is taken into account in (b)[61j.

It should be noted that in the present case the trajectoiy calculations were carried out for coplanar collisions with the vibration of HCl (DCl) fiozen [47], A trajectory was assumed to be reactive if it reached a point on the top of the electronic barrier. There are no corrections of the barrier height due to the vibrational zero-point energy effect in this case. These trajectory results are therefore more directly comparable with the results of the kinematic mass model than the 3-dimensional quasiclassical trajectroiy calculations discussed in the previous case. 

Figure 9. Rotational dependence of the reaction cross section for O + HCl and O + DCl reactions at Ete,ns= 10 kcaVmol. ( ) classical trajectory results [48] ( ) results of the kinematic mass model with the dependence of the distribution of collisions at the barrier on reagent rotation taken into account (o) results of the same model with the effect of rotation on the distribution of collisions neglected[61].

Figure 11. Rotational energy , dependence of the cross section for O + HCl and O + DCl reactions at E uk = 10 kcal/mol. Compared are the results of the classical trajectory calculations ( ) [47], kinematic mass model results which only include the energetic effects of the reactant rotation (o). kinematic mass model results which include rotational effects on the distribution of collisions with the barrier in addition to the rotational energetic effects ( ), and the kinematic mass model results for rotationally unexcited reactants 0 = 0) and the translational kinetic energy increased by the amoimt of (A) [62].

Perdih, M., Miklavc, A. and Smith, LW.M. (1997) Kinematic mass model of activated bimolecular reactions Molecular shape effects and zero-point energy corrections. J. Chem. Phys. 106, 5478-5493. 

Perdih, M., Smith, I.W.M. and Miklavc, A. (1998) Kinematic mass model of activated bimolecular reactions Reactions of vibrationaUy excited reactants. J. Phys. Chem. A 102, 3907-3915. 

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 =... 

---