Multireference Theoretical Investigations On The Small Molecule Containing Peroxy Radical

The small molecule containing peroxy radicals is one of the important intermediates of the atmospheric chemical and photochemical process. Considering the influence of the peroxy radical on the atmospheric environment, more and more scientists began to pay attention to the reaction which the peroxy radical participate in, and also made some progress in theory and experiment. As the protective layer of the earth, the ozone hole problem has been highly recognized in the air pollution. The formation of ozone requires the reaction of O2 molecules with the single atom O, since O2 is widespread, so the generation of single atom O is the key to solve the problem. Because of peroxy radical easy to lose the O atom and there is a large number of peroxy radical in the troposphere, so this kind of small molecule has been widespread attentioned. Through a great deal of researches, scientists hope to solve the problem through the study of the small molecules containing the peroxy radicals photochemistry process. After the continuous exploration of scientists, discoveried that the phenylperoxyl radicals can produce a O(3Pg) in the light conditions, and the experimental results have been observed. But we are not aware of the reaction path of the phenylperoxyl radicals photodissociation reaction.In this paper, by using MOLCAS software we report performed a high level ab initio study on the low-lying electronic states of C6H5 OO. Through the photodissociation reaction of phenylperoxyl radical potential energy surface, the reaction mechanism and the reaction path are studied. The results of this study provide theoretical support for the future research on the atmosphere, combustion and interstellar chemistry. The main contents are summarized as follows:At the contracted ANO-L basis set, utilizing complete active space self-consistent field(CASSCF) and multiconfiguration second-order perturbation theory(CASPT2) method, and. the active space is CAS(15, 13). The ground state and low excited state geometries, energies and electron configuration properties have been calculated. Considering the influence of the electronic excitation to the geometrical configuration, the C1 symmetry is used in all the calculations. Under these conditions, the theoretical calculation results of the vertical excitation energy and the adiabatic ionization energies are very close to the experimental values.The potential energy curves for the four lowest states associated with the lowest dissociation limit of C6H5 OO radical. The calculated results clearly assigned the experimentally observed photodissociation channels leading to C6H5O(X2A, 22A) + O(3Pg) and C6H5(X2A) + O2(X3Σg-, 11Δg,11Σg+). Along the PECs of D2, two main paths may occur. The first one is through a TS-D1(3.25 eV) dissociate to the C6H5(X2A) + O2(11Δg). The second mechanism is that the direct O-loss dissociation occurs from the D2 state, which supports the observation of the two major photoproducts, O2 and O.