A density functional method DFT/B3P86 with relativistic effective core potential basis for U and 6-311+G(d) basis for O is used to study the energy gaps and harmonic frequencies of ground state UO molecule under different inner radiation fields ranging from -0005 to 0005 a . u.. The results show that the harmonic frequency ωe is close to experimental value 8198cm-1 under different inner radiation fields. The energy gap is found to increase with the increasing inner radiation field. The electron of occupied orbital is difficult to stimulate to empty orbital and to transform into excited station. The UO molecular is more stable in inner radiation fields, so it can prevent O2, CO2 and so on to proliferate to superficial inner layer and then to corrode the uranium surface, which contributes to the uranium corrosion prevention in inner radiation fields.
