Dual-level direct dynamics studies on the reaction Cl + CHBr(2)Cl

Theoretical investigations are carried out on the multichannel reaction CHBr(2)Cl + Cl by means of direct dynamics methods. The minimum energy path (MEP) is obtained at the BH&H-LYP/6-311G(d,p) level, and energetic information is further refined at the CCSD(T)/6-311+G(2df,2p) (single-point) level. The rate constants for three reaction channels, H-abstraction, Br-abstraction, and Cl-abstraction, are calculated by using the improved canonical variational transition state theory (ICVT) incorporating with the small-curvature tunneling (SCT) correction. The theoretical overall rate constants are in good agreement with the available experimental data and are found to be k=2.58 x 10(-15) T(1.18) exp(-861.17/T) cm(3)molecule(-1)s(-1) over the temperature range 200--2400 K. For the title reaction, H-abstraction reaction channel is the major channel at the lower temperatures, while as the temperature increases, the contribution of Br-abstraction reaction channel should be taken into account. At 2180 K, the rate constants of these two pathways are equal. Cl-abstraction reaction channel is minor channel over the whole temperature region.