Direct Dynamics Simulations of the ³CH₂ + ³O₂ Reaction at High Temperature

Direct dynamics simulations with the M06/6-311++G(d,p) level of theory were performed to study the ³CH₂ + ³O₂ reaction at 1000 K temperature on the ground state singlet surface. The reaction is complex with formation of many different product channels in highly exothermic reactions. CO, CO₂, H₂O, OH, H₂, O, H, and HCO are the products formed from the reaction. The total simulation rate constant for the reaction at 1000 K is (1.2 ± 0.3) × 10^-12 cm³ molecule^-1 s^-1, while the simulation rate constant at 300 K is (0.96 ± 0.28) × 10^-12 cm³ molecule^-1 s^-1. The simulated product yields show that CO is the dominant product and the CO:CO₂ ratio is 5.3:1, in good comparison with the experimental ratio of 4.3:1 at 1000 K. On comparing the product yields for the 300 and 1000 K simulations, we observed that, except for CO and H₂O, the yields of the other products at 1000 K are lower at 300 K, showing a negative temperature dependence.