中文摘要：

用密度泛函方法B3LYP／SDD／6—311＋＋G^＊＊计算了YH2的微观性质．并用分子总能量中的振动能Ev代替固态能量，振动熵SEv代替固态熵的近似方法，以及考虑到电子能量的变化，计算了固态YH2（D，T）的焓H和熵S，得到不同温度下Y与H2，D2，T2反应的△H^Θ，△S^Θ，△G^Θ及氢化反应平衡压力，导出了与温度的依赖关系．计算结果表明，YH2（s）的生成热为199．25kJ·mol^-1，与实验值210．00及225．94kJ·mol^-1非常接近，说明近似方法的正确性．

英文摘要：

Density functional （B3LYP/SDD/6-311＋＋G^＊＊） method with relativistic effective core potential （RECP） has been used to compute the microcosmic characters of YH2, and to calculate energy E, thermodynamic functions of YH2（D, T）. Considering the characteristics of different motion types, the vibration energy and vibration entropies of the molecules were assumed to be the corresponding values of their solid states. △H^Θ, △S^Θ, △G^Θ and hydrogen isotope equilibrium pressures of the hydrogenation reaction at different temperatures have been calculated based on this approximation. The enthalpy of formation of YH2（s） at 298 K is 199.25 kJ·mol^-1 , Which is close to the experimental value 210.00 and 225.94 kJ·mol^-1. The results show that the present method is feasible to theoretical study on hydrogen storage materials.