Ab initio/density functional theory and multichannel RRKM study for the ClO + CH2O reaction

Area of Science:

• Chemical Kinetics
• Atmospheric Chemistry
• Theoretical Chemistry

Background:

• The CH(2)O + ClO reaction is relevant to atmospheric chemistry.
• Understanding reaction pathways and rate constants is crucial for atmospheric modeling.

Purpose of the Study:

• To investigate the potential energy surface and calculate rate constants for the CH(2)O + ClO reaction.
• To identify dominant reaction channels and their associated energy barriers.

Main Methods:

• Quantum chemical calculations using QCISD(T)/6-311G(2d,2p)//B3LYP/6-311G(d,p) level of theory.
• Rate constant calculations using Transition State Theory (TST) and multichannel Rice–Ramsperger–Kassel–Marcus (RRKM) theory.

Main Results:

• The overall rate constant was determined to be k(200-2000K) = 1.19 x 10(-13)T(0.79) exp(-3000.00/T) cm(3) molecule(-1) s(-1).
• The formation of HOCl + HCO was identified as the dominant exothermic reaction channel with a low barrier (5.0 kcal/mol).
• The calculated rate constant at 250 K agreed well with experimental upper limit data.

Conclusions:

• The HOCl + HCO channel is the primary pathway for the CH(2)O + ClO reaction.
• Significant energy barriers exist for the forward and reverse decomposition of HOCl, suggesting its stability under ground electronic state conditions.