DFT investigations of structural and energetical features of [H₂O₂]ⁿ (n=−1,0,1) potential energy surfaces

Oxywater (H₂OO) is a proposed structural isomer of hydrogen peroxide (HOOH) that may serve as a transient intermediate in oxidation reactions. This molecule has been described by Pople et al. and Meredith et al. at ab initio level (HF and post HF). We have performed DF calculations at the local level of approximation and nonlocal level through various gradient‐corrected functionals. In addition the geometry has been optimized also by using a large polarized basis set in correlated (MP2 and CCSD(T) levels) ab initio MO calculations. Comparisons are made and this isomers seems to be a severe test for the accuracy of these functionals. Extensions towards the modelisation of the anionic and cationic structures, the interconversion and dissociation pathways are discussed and compared to the experimental data. Attention has been devoted to the monoanion analogues of hydrogen peroxide which equilibrium geometry is predicted to be almost planar with one hydrogen atom bridging both oxygen atoms and the unpaired electron mostly localized on the outer oxygen atom.