Two versions of the double-layered composite methods, including the restricted open-shell model chemistry based on the complete basis set quadratic mode (DL-ROCBS-Q) and the extrapolated CBS limit of electronic energy on the basis of the coupled cluster with single, double, and noniterative triple excitations with the hierarchical sequence of the correlation-consistent basis sets (DL-RCCSD(T)/CBS), were developed to calculate the energetic reaction routes for the systems involving 13/14 heavy atoms with good balance between efficiency and accuracy. Both models have been employed to investigate the oxidation reactions of heptafluoroisobutyronitrile ((CF3)2CFCN) with hydroxyl radical. The (CF3)2CFCN + OH reaction is dominated by the C–O addition/elimination routes as bifurcated into trans- and cis-conformations. Although the formation of isocyanic acid or hydrogen fluoride is highly exothermic, the major nascent product was predicted to be the less exoergic cyanic acid. Preference of the product channels could be tuned by the single water molecule in the presence of the H2O–HO complex. The production of amide compound was found to be the most significant route accompanied by the OH regeneration. Moreover, the OH radical could be an efficient catalyst for the hydrolysis of (CF3)2CFCN. Implication of the current theoretical results in the chemistry of (CF3)2CFCN for both atmospheric sink and potential dielectric replacement gas was discussed.

Ab intitio molecular dynamics simulation of the electronic structure of the aqueous superoxide anion (O2−) has been carried out using the Car−Parrinello density functional theory at 298 and 310 K. The modeling system consists of one O2− solvated in 31 water molecules. On the basis of our 40 ps production run, the novel mechanism and the nature of the hydration of the superoxide anion in a relatively big aqueous environment have been revealed by using various radial distribution functions. The averaged coordinated water number was estimated to be 4.5. The calculated microscopic configurations of the first solvation shell are in good agreement with the experimental results. The vibrational frequency of the solvated O2− anion was red-shifted significantly in comparison with that of the free radical anion in the gas phase. The diffusion coefficient of O2− was estimated to be about 8 × 10−5 cm2/s at 298 K. Comparisons with the previous force-field-based classical molecular dynamics simulations have been made, and the differences were discussed.