锆氢化反应热力学函数的计算

用B3LYP/SDD密度泛函方法计算了ZrH的微观性质,气态ZrH(D,T)的能量(E),熵(S)以及 Zr与氢同位素气体反应的热力学函数.在ZrH(s)、ZrD(s)和ZrT(s)的E和S的计算中,近似以分 子总能量中的振动能Ev代替固态能量,以电子和振动熵SEv代替固态熵.在这种近似下,计算了 不同温度下Zr与H2、D2、T2反应的ΔH、ΔG、ΔS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,ZrH(s)的生成热为161.34 kJ穖ol-1,与实验值(173.5 kJ穖ol -1)接近,表明这种近似处理方法是合理的,可以用于研究贮氢材料氢化反应的热力学.

Quantum Mechanical Calculation of the Adsorption of Hydrogen Isotopes on Metallic Zirconium

Density functional (B3LYP/SDD) method with relativistic effective core potential (RECP) have been used to optimize the structure of ZrH,and to calcula te energy E,entropy S and enthalpy H of ZrH,ZrD and ZrT.Considering the characte ristics of different types of motion,the vibration energy or electronic and vibr ation entropy of the molecules are assumed to be the corresponding values of the ir solid states.ΔH,ΔG,ΔS and hydrogen isotope equilibrium pressures of the hydrogenating reaction have been calculated based on this approximation.The enthalpy of formation of ZrH(s) calculated at 298 K is 161.34 kJ mol-1 which i s close to the experimental value 173.5 kJ mol-1.The results show that the pre sent method is reasonable to the theoretical study of hydrogen storage materials .