A multiproperty empirical potential energy surface for the reaction H + Br₂→HBr + Br

We have made systematic variations in our previously reported potential energy surface for the reaction H + Br₂, and we have tested the new potential energy surfaces by extensive trajectory calculations. We have attempted to find a surface that simultaneously displays as many as possible of the attributes of this reaction in agreement with experiment and that has a bent transition state with a weak bending force constant for consistency with recent ab initio calculations. The best surfaces overall, called surfaces 18M and 19M, are in reasonable agreement with experiment for the angular scattering distribution, the reaction cross section as a function of translational energy, the average vibrational and rotational energies of the product HBr, and the thermal rate constant at room temperature. They are less accurate for the deuterium isotope effect and the breadth of the product vibrational distribution at room temperature, and for the average product translation energy at high collision energy.