Theoretical study on the gas phase rate constants of NO+ HO2 reaction

We used weak collision master equation (RRKM) simulation and TST and VTST theories to calculation of accurate dynamics of the reaction of NO with HO2. The reaction occurs over a multiwell, multipath potential energy surface which is based on the calculations at the single determinant methods. The singles determinant methods for optimization of multipath potential energy surface are MP2 [1] and M06-2X [2,3] and B3LYP [4,5] with 6-311++g(3df,3pd), aug-ccpVTZ and aug-cc-pVQZ basis sets. Our proposed potential energy surface consists of one pre reactive van der Waals complex .the Lennard-Jones potential is used for solving the master equation. The Lennard-Jones parameters of ε/K =107.400 and σ =3.458 Å for HO2 and ε/K=97.530 and σ =3.621 Å for NO are used to model the collision between the collider gases. The main products of the considered reaction at room temperature are HNO3, NO2, O2 (X3Σg-), and OH. Rate constant of all reaction pathways are computed by TST and VTST theories for bimolecular reactions and RRKM theory is used for unimolecular reactions. The pressure dependent rate constant for major pathway calculated with RRKM theory.