Structure of hydrogen tetroxide in gas phase and in aqueous environments: relationship to the hydroperoxyl radical self-reaction

Theoretical investigation of the structures and spectroscopic properties of (H2O4)n (n = 1–4) clusters

“…The absolute energies ( E , in hartree), ZPVE (in kcal/mol), and 50% BSSE (in kcal/mol) for the (H 2 O 4 ) n ( n = 1–4) clusters are listed in Table S1 (Supporting Information). The cyclic HOO dimer ( 1d ) was predicted to be the global minimum structure with the B3LYP and CAM‐B3LYP methods (with all basis sets), while the chain‐structure ( 1a ) with C 1 symmetry was calculated to be the global minimum structure by high‐level calculations (MP2 and CCSD(T)), in agreement with the most recent ab initio calculations . The energy differences between the chain structures ( 1a – 1c ) were less than 1 kcal/mol at all levels of theory and the results agree with previous theoretical predictions …”

“…The binding energy between H 2 O 4 and H 2 O was calculated to be −6.84 kcal/mol, which indicates that the self‐aggregate of the H 2 O 4 dimer was more favorable than its solvation by a molecule of water. Recently, the relative stability of the H 2 O 4 – n H 2 O ( n = 1–2) complex was compared with the (HO 2 ) 2 – n H 2 O complex by Martins‐Costa et al They concluded that even though the effect of hydration slightly reduced the relative stability of H 2 O 4 with respect to two separated HO 2 radicals, H 2 O 4 is significantly favored with respect to the (HO 2 ) 2 dimer in a water environment …”

“…Recently, the enthalpies and Gibbs free energies of the singlet (HO 2 ) 2 and three conformers of the chainlike H 2 O 4 were computed by Sprague and Irikura . Additionally, Martins‐Costa et al theoretically studied the relative stability of H 2 O 4 with respect to the HO 2 radical dimer and the structure of H 2 O 4 in various water environments …”

Permutation-Invariant-Polynomial Neural-Network-based Δ-Machine Learn-ing Approach: A Case for the HO2 Self-reaction and its Dynamics Study

“…Indeed, there exists a relatively stable intermediate between the two HO2 radicals, namely the H2O4 intermediate (the HO2 radical dimer) on the triplet state surface, whose energetics and spectroscopic characterization have also been scrutinized extensively by theory and experiment. [25][26][27][28][29][30][31][32] As shown in Figure 1, our calculations show that another high-energy pathway via H2OO + O2 leads to the same products H2O2 + O2. To the best of our knowledge, it is the first time that this reaction path is reported.…”

Permutation-Invariant-Polynomial Neural-Network-based Δ-Machine Learn-ing Approach: A Case for the HO2 Self-reaction and its Dynamics Study

“…Indeed, there exists a relatively stable intermediate between the two HO2 radicals, namely the H2O4 intermediate (the HO2 radical dimer) on the triplet state surface, whose energetics and spectroscopic characterization have also been scrutinized extensively by theory and experiment. [25][26][27][28][29][30][31][32] As shown in Figure 1, our calculations show that another high-energy pathway via H2OO + O2 leads to the same products H2O2 + O2. To the best of our knowledge, it is the first…”