jp067178d_si_001.pdf (38.62 kB)

# Ab Initio Study of the ClO + NH_{2} Reaction: Prediction of the Total Rate Constant and
Product Branching Ratios^{†}

journal contribution

posted on 2007-05-17, 00:00 authored by R. S. Zhu, M. C. LinThe mechanism for ClO + NH

_{2}has been investigated by ab initio molecular orbital and transition-state theory calculations. The species involved have been optimized at the B3LYP/6-311+G(3df,2p) level and their energies have been refined by single-point calculations with the modified Gaussian-2 method, G2M(CC2). Ten stable isomers have been located and a detailed potential energy diagram is provided. The rate constants and branching ratios for the low-lying energy channel products including HCl + HNO, Cl + NH_{2}O, and HOCl +^{3}NH (X^{3}Σ^{-}) are calculated. The result shows that formation of HCl + HNO is dominant below 1000 K; over 1000 K, Cl + NH_{2}O products become dominant. However, the formation of HOCl +^{3}NH (X^{3}Σ^{-}) is unimportant below 1500 K. The pressure-independent individual and total rate constants can be expressed as*k*_{1}(HCl + HNO) = 4.7 × 10^{-8}(*T*^{-1.08}) exp(^{-129}/*),*_{T}*k*_{2}(Cl + NH_{2}O) = 1.7 × 10^{-9}(*T*^{-0.62}) exp(^{-24}/*),*_{T}*k*_{3}(HOCl + NH) = 4.8 × 10^{-29}(*T*^{5.11}) exp(^{-1035}/*), and*_{T}*k*_{total}= 5.0 × 10^{-9}(*T*^{-0.67}) exp(^{-1.2}/*), respectively, with units of cm*_{T}^{3}molecule^{-1}s^{-1}, in the temperature range of 200−2500 K.