自辐射场下UN2分子的光谱研究∗

摘要

A density functional method DFT/B3P86 with relativistic effective core potential basis for U and 6-311+G(d) basis for N is used to study the energy gap and harmonic frequency of UN2 ground state molecule under the action of the uranium-produced spontaneous radiation fields ranging from −0.005 to 0.005 a.u.. The results show that UN2 has an anti-symmetry expansion vibrational frequency ν3 (σg) that is close to experimental value 1051.1 cm−1 under the action of different spontaneous radiation fields, and a symmetrical expansion vibrational frequency ν1(σg) that is close experimental value 1008.3 cm−1. The energy gap is found to decrease with increasing the spontaneous radiation field. The electron which occupies an orbital is easy to excite to empty orbital and transform into an excited state. The UN2 molecule turns unstable in the spontaneous radiation field;N2, O2 and others more easily diffuse into the surface interior, thus corroding the uranium surface and aggravating the corrosion of uranium in the spontaneous radiation field.%对铀原子和氮原子分别使用相对论有效原子实势和6-311+G(d)基组,采用优选的密度泛函B3P86方法,研究了铀本身产生自辐射场(−0.005—0.005 a.u.)作用下UN2基态分子的能隙Eg和谐振频率ν.结果表明： UN2分子在自辐射场中反对称伸缩振动频率ν3(σg)和对称伸缩振动频率ν1(σg)与实验值1051.1 cm−1和1008.3 cm−1基本符合；Eg随自辐射场场强的增大而趋于减少,占据轨道的电子容易被激发至空轨道而形成激发态； UN2分子在自辐射场中趋于不稳定, N2, O2等更容易扩散到表面内层而腐蚀铀表面,加剧了铀在自辐射场中的腐蚀.