Ab Initio and Kinetic Calculation for the Abstraction Reaction of Atomic O(3P) with SiH4

The reaction of O( 3 P) with silane was studied theoretically. The detailed mechanism was revealed for the first time. Two nearly degenerate transition states of 3 A‘ ‘ and 3 A‘ symmetries were located for the title reaction. Geometries were optimized at the UMP2 level with the 6-311G(2d,2p) basis set. The QCISD(T) level with the 6-311++G(3df,3pd) basis set was used in the final single-point energy calculations. On the basis of the ab initio data, the kinetic nature was studied using canonical variational transition-state theory (CVT) with small-curvature tunneling effect (SCT) correction. The rate constants were calculated over a wide temperature range of 200−3000 K. The CVT/SCT rate constants exhibit typical non-Arrhenius behavior, a three-parameter rate−temperature formula was fitted as follows: k ( T ) = (1.53 × 10 -17 ) T 2.25 exp(−834.32/ T ) (in units of cm 3 molecule -1 s -1 ). The calculated CVT/SCT rate constants match well with the experimental values.