A Density functional theory investigation of the reactions of Fe and FeO with O

Nakazawa, Tetsuya; Kaji, Yoshiyuki  

The reactions of Fe and FeO with O and the products of these reactions are investigated at the B3LYP/6-311+G(d) level. The reactions are considered in terms of the calculated potential energy surfaces, the interaction energies between reactant species, and the energies required to populate the higher electronic states such as the excited states of Fe(F, F) and O(). It is found that the reactions of Fe with O are endothermic and that the direct formation of dioxide OFeO is due to an ionic interaction of Fe with O. Furthermore, the diabatic transitions from the covalent and ionic surfaces onto another ionic surface with energy barriers allow the Fe + O reaction to proceed toward the formation of OFeO. There are other paths corresponding to the vertical excitation from peroxide Fe(O) to dioxide OFeO. The OFeO + O reactions are found to endothermically produce the 2- and -(O)FeO complexes, and the low-lying states of complexes are found to be closely located in energy. The CCSD and CCSD(T) single point energy calculations are performed with the structures optimized at the B3LYP level. The results of NBO and Mulliken analyses and the harmonic vibrational frequencies are presented.