The potential energy surface of OH anion reaction with CH3OOH: Theoretical investigations

Removing ROOH in the atmosphere is important because they can lead to the redistribution of HO and ROx radicals, which regulate the oxidation capacity of the atmosphere. The MP2 method and the B3LYP and PBEO DFT functionals, with 6-31++G** and aug-cc-pVDZ basis sets were employed to determine the geometries, reaction paths and mechanisms of OH- + CH3OOH reaction. Single point energy calculations were carried out at CCSD(T)/aug-cc-pVDZ level of theory served as benchmark. Although B3LYP energies gives the best agreement to the benchmark, it failed to locate TS1. PBE0/6-311+G(d,p) is chosen as an appropriate method for the dynamics simulations. Four product channels are observed, where CH3OO- + H2O and H2O + CH2O + HO- are competitive due to the similar barrier height, and H2O + CH2(OH)O- is the most exothermic product, and in contrast, CH3OH + HOO- is the least feasible one. The PES results are not consistent with the experimental observation where product H2O + CH2(OH)O- is not found, which might attribute to a "rough" landscape of PES after passing a rate controlling transition state, implying a non-IRC behavior for this reaction. (C) 2016 Elsevier B.V. All rights reserved.