(209e) Formation and Decomposition Kinetics of HONO and HNO2

The HNO₂ system â?? cis-HONO, trans-HONO, and HNO₂ â?? are important intermediates in the combustion of nitrogen. These isomers are typically formed either from H-abstraction or disproportionation. To date, most experimental and theoretical work on the HNO2 potential energy surface has focused on the chemically activated reaction H + NO₂â?? OH + NO. The isomerization and decomposition kinetics of the HNO2 isomers has received considerably less attention.

This talk will present recent theoretical work on the isomerization and thermal decomposition of cis-HONO, trans-HONO, and HNO₂. For the stationary points, geometry optimization and normal mode analysis was done using CCSD(T)/cc-pVQZ. Five post-coupled cluster methods were used to further improve the electronic energy. The tight transition state for isomerization between trans-HONO and HNO2 was computed using conventional transition state theory with rigid-rotor harmonic oscillator approximations. For the three H + NO₂pathways and the two OH + NO pathways, variable reaction coordinate transition state theory was used. The active space was 14 electrons in 11 orbitals.

The final part of the talk will focus on the relative importance of including all three isomers in kinetic models versus the simplicity of treating all three as a single, lumped species.