title: DFT and ab initio direct dynamics studies on the hydrogen abstraction reactions of chlorine atoms with CH(4-n)F(n) (n = 1-3).
abstract: A direct dynamics study is carried out for the hydrogen abstraction reactions Cl + CH(4-n)F(n) (n = 1-3) in the temperature range of 200-1,000 K. The minimum energy paths (MEPs) of these reactions are calculated at the BH&H-LYP/6-311G(d,p) level, and the energies along the MEPs are further refined at the QCISD(T)/6-311+G(2df,2p) and QCISD(T)/6-311+G(d,p) (single-point) level. The rate constants obtained by using the improved canonical variational transition state theory incorporating small-curvature tunneling correction (ICVT/SCT) are in good agreement with the available experimental results. It is shown that the vibrational adiabatic potential energy curves for these reactions have two barriers, a situation similar to the analogous reactions CH(3)X+Cl (X=Cl, Br). The theoretical results show that for the title reactions the variational effect should not be neglected over the whole considered temperature range, while the small-curvature tunneling effect is only important in the lower temperature range. The effects of fluorine substitution on the rate of this kind of reactions are also examined.
authors.affiliation: Institute of Theoretical Chemistry, State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130023, People's Republic of China.
authors.forename: Jing-Fa
authors.initials: JF
authors.lastname: Xiao
authors.forename: Ze-Sheng
authors.initials: ZS
authors.lastname: Li
authors.forename: Jing-Yao
authors.initials: JY
authors.lastname: Liu
authors.forename: Li
authors.initials: L
authors.lastname: Sheng
authors.forename: Chia-Chung
authors.initials: CC
authors.lastname: Sun