Theoretical Study on Impact of Single Water Molecule on OH+O₃ Reaction

Quantum chemical calculations are performed to study the reactions of OH and ozone with-out and with water to estimate whether the single water molecule can decrease the energy barrier of the OH radical reaction with ozone. The calculated results demonstrate that the single water molecule can reduce the activated barrier of the naked OH+O₃ reaction with the value of about 4.18 kJ/mol. In addition, the transition state theory is carried out to determine whether the single water molecule could enhance the rate constant of the OH+O₃ reaction. The computed kinetic data indicate that the rate of the ozone reaction with the formed complexes between OH and water is much slower than that of the OH+O₃ reaction, whereas the rate constant of OH reaction with the formed H₂O…O₃ complex is 2 times greater than that of the naked OH radical with ozone reaction. However, these processes in the atmosphere are not important because the reactions can not compete well with the naked reaction of OH with ozone under atmospheric condition.