(The) modeling of CH$_3$ + HCl potential energy surface and the calculation of reaction rate constants

Abstract

We modeled the new potential energy surface of $CH_3+HCl$→$CH_4+Cl$ system and calculated the rate constant in the same one. The new potential energy surface(PES) is based on the modified Raff Surface and have a good quality in that the geometry and the activation energy (1.25 kcal/mol) as expected from the experiments and G1 Gaussian calculation result and experimental data (1.45 kcal/mol). This surface adapts the switching parameters which simultaneously change with the angles and geometry. Our calculation was performed under the assumption that the above reaction progresses adiabatically and is two step reaction, which the first has no classical saddle point, but has variational transition state, and the second has one saddle point at which breaking of vibration symmetry occurs. We expect our result to be applied to the $CH_3$+HX→$CH_4$+X reaction(X : Br or I) which has the negative activation energy.