Direct ab initio dynamics studies of the reactions of HNO with H and OH radicals

Ab initio calculations using the UMP2 and UQCISD methods with correlation consistent double-zeta and triple-zeta basis sets were applied to study the reactions of HNO with H and OH radicals. The classical energy barrier for the abstraction H + HNO → H2 + NO is 0.5 kcal/mol. The reaction path of OH + HNO is: OH + HNO → HNO(OH)-complex → TS → NO(H2O)-complex → H2O + NO with no energy barrier relative to OH + HNO entrance channel. Canonical and microcanonical variational transition state theory calculations were carried out for these reactions (200–2500 K) and compared with available experimental kinetic data.