铀与水蒸气体系的热力学性质计算

应用Gaussian 98程序对U-H₂O体系所有可能的构型进行优化计算-采用密度泛函 理论的B3L YP方法和MP2方法，对铀原子采用相对论有效原子实势及(6s5p2d4f)/［3s3p2d2f］收缩价基 集合，氧、氢原子采用6-311G^**全电子基集合-计算得到了6种五重态的相对稳 定结构 的电子状态、几何结构、能量、谐振频率、力学性质和电性质等-结果表明，H₂ O蒸汽在金 属铀表面的反应首先是铀和氧的相互作用-对C_{2v关键词： 密度泛函理论 B3LYP 分子结构 热力学函数}

The thermodynamical calculations of uranium-water vapor system

In this paper, we study the relative stable molecular structures of uranium-wate r vapor system- For the uranium atom were used the relativistic effective core p otential and contracted valued basis sets (6s5p2d4f)/3s3p2d2f], and for oxygen and hydrogen atoms were used 6-311G^** basis sets- We obtain the elect ronic state, geometric structure, energy, harmonic frequency, mechanical property, et c-，of these six quintuple relative stable structures- It indicated that the first step of uranium-water vapor reaction is the interaction of uranium and oxyg en atoms- The thermodynamical stability of UOH₂(⁵A₁) was calculated an d its disassociation Gibbs free energy ΔG°decreased with increasing temper ature -The result showed that low temperature favoured its existence-