Calculation of Energy Barriers for Elementary Steps in Hydrogen-Halogens Reactions

4 CALCULATION OF ENERGY BARRIERS FOR ELEMENTARY STEPS IN HYDROGEN-HALOGEN REACTIONS 

The calcnlation of the energy barriers for the elementary reactions between X and Hj, H and HX and H and X2, which are involved in the mechanisms 12.I-12.in has been presented in Chapter 6. Using the ISM formalism and the structural parameters of Appendix 111, data have been calculated for chlorine, bromine and iodine and are presented in Table 12.2. 

The calculation of the energy barrier for the elementary reaction between molecular halogens and hydrogen, 

The extension of each reactive bond from its equilibrium length up to the transition state can be estimated through a generalisation of eq. (6.57) 

Here one considers the sum of four equilibrium bond lengths, since this is the number of the reactive bonds in the transition state. 

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