Exploring the potential energy surface of the hydrogen abstraction reaction from hydrochloric acid with hydrogen and methyl radicals using ab initio and density functional theory methods. An example of a polar radical hydrogen abstraction reaction

Ab initio and density functional theory (DFT) studies were performed on the H + HCl --> H-2 + Cl and CH3 + HCl --> CH4 + Cl reactions in order to computationally describe their potential energy surfaces. It was demonstrated that the most widely used ab initio and DFT methods can not reproduce experimental energies. While many of the ab initio methods generated high activation barriers, the majority of the DFT methods generated negative activation barriers. The suitability of some ab initio and DFT methods for computing the energies of these reactions was discussed.