Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4442671 | Atmospheric Environment | 2008 | 10 Pages |
Density functional theory and ab initio molecular orbital calculations have been employed to determine the structures and energetics of the nitrooxyalkyl peroxy radicals arising from the NO3-initiated oxidation of isoprene. Geometry optimizations of the peroxy radicals are performed using density functional theory at the B3LYP/6-31G(d,p) level and single-point energies are computed using second-order Møller-Plesset perturbation theory and the coupled-cluster theory with single and double excitations including perturbative corrections for the triple excitations (CCSD(T)). The zero-point corrected energies of the nitrooxyalkyl peroxy radicals are 37–43 kcal mol−1 more stable than the separated NO3, O2 and isoprene reactants at the CCSD(T)/6-31G(d)+CF level. The rate constants for the addition of O2 to the NO3–isoprene adducts are calculated using the canonical variational transition state theory (CVTST), with an overall rate constant of 3.8×10−12 cm3 molecule−1 s−1. The results provide the isomeric branching ratios between eight nitrooxyalkyl peroxy radicals.