The Paper Is Devided Into Two Sections As Shown Below.

The paper is devided into two sections as shown below.1. An ab intio study on the reaction of bromine atom with ethyleneWe examined this reaction at the CCSD(T)/aug-cc-pVDZ//MP2/6-311+G(d, p) level of theory. The results indicate that the reaction bromine atom with ethylene is devided into two categories: (1) The free radial of ethylene was substituted by bromine atom. (2) The hydrogen atom of ethylene was abstracted by bromine atom.It is found that as bromine atom approaches ethylene, initially they form a stable van der Waals complex I_add, rather than reach the transition state TS_add directly as suggested by others. The existence of this prereaction complex justifies the high regio-selectivity observed in the collision reaction between bromine atom and ethylene. As to the dissociation of brooroethyl radical, in addition to the direct departure of hydrogen atom, an indirect pathway is shown energetically accessible.In the hydrogen-abstraction reaction, the bromine atom was collided with the hydrogen atom along the OH bond. The bond angle of ∠BrH₁C₁ of the transition structure TS_abs is 176.05°. IRC were performed for the optimal reaction path and the suboptimal reaction path.2. An ab intio study on the reaction of chlorine atom with trans-butadieneWe examined this reaction at the QCISD(T)/aug-cc-pVDZ//MP2/6-311G(d, p) level of theory. The results indicate that the reaction chlorine atom with trans-butadiene is devided into two categories: (1) The free radial of trans-butadiene was substituted by chlorine atom. (2) The hydrogen atom of trans-butadiene was abstracted by chlorine atom.We can that as chlorine atom approaches trans-butadiene, initially they form a free radical intermediate. The energy of the transition structure is smaller than the sum of energies of react chlorine atom and the trans-butadiene because of the existence of a prereaction complex. So through our calculations the chlorine atom could added to the first carbon atom of the trans-butadiene.In the hydrogen-abstraction reaction, the chlorine atom was collided with the hydrogen atom along the OH bond. The bond angle ∠C1HC of the three transition states...