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

Area of Science:

• Chemical Kinetics
• Computational Chemistry
• Reaction Dynamics

Background:

• The reaction between triplet methylene (³CH₂) and triplet oxygen (³O₂) is crucial in combustion and atmospheric chemistry.
• Understanding the product distribution and kinetics is essential for modeling these processes.

Purpose of the Study:

• To investigate the reaction mechanism and product yields of ³CH₂ + ³O₂ using direct dynamics simulations.
• To determine the rate constants and analyze the temperature dependence of the reaction products.

Main Methods:

• Direct dynamics simulations were performed using the M06/6-311++G(d,p) level of theory.
• Simulations were conducted at 300 K and 1000 K to analyze temperature effects.

Main Results:

• The reaction produces multiple products including CO, CO₂, H₂O, OH, H₂, O, H, and HCO.
• Carbon monoxide (CO) was identified as the dominant product, with a CO:CO₂ ratio of 5.3:1 at 1000 K, closely matching experimental data.
• A negative temperature dependence was observed for most products, with yields decreasing at higher temperatures (1000 K vs. 300 K), except for CO and H₂O.

Conclusions:

• The ³CH₂ + ³O₂ reaction is complex, yielding a variety of products.
• The simulation results align well with experimental findings, particularly regarding the CO:CO₂ ratio.
• The observed negative temperature dependence for several products provides valuable insights into the reaction dynamics.