锆钴合金氢化反应热力学函数的计算

在有效原子实势近似下,采用Gaussian 98计算程序及B3LYP/SDD密度泛函方法计算得到了ZrCo和ZrCoH分子的结构、力常数、离解能,能量(E)、熵(S)以及ZrCo与氢同位素气体反应的热力学函数.在固态ZrCo、ZrCoH(D、T)的E和S的计算中,近似以气态分子总能量中的振动能EV代替该分子处于固态时的振动能量,以电子运动和振动运动熵SEv代替分子处于固态的熵,在这种近似下,计算了不同温度下ZrCo与H2、D2、T2反应的ΔH、ΔG、ΔS及氢化反应平衡压力,导出了氢化反应温度与平衡压力的依赖关系.计算得出：ZrCoH、ZrCoD、ZrCoT的生成焓(398～598 K）分别为82.81、81.54和80.49 kJ•mol－1,与实验结果有很好的一致性,表明这种近似处理方法是合理的,可以用于一些未知氢化物的热力学函数的近似计算.

Ab initio of the Thermodynamic Function for the Hydrogenating of Zirconium-Cobalt Alloy

Density functional (B3LYP/SDD) method with relativistic effective core potential (RECP) have been used to optimize the structure of ZrCo and ZrCoH,and to calculate energy E,entropy S and enthalpy H of ZrCoH(D,T).Considering the characteristics of different motion types,the vibration energy or electronic and vibration entropy of the molecules is assumed to be the corresponding values of their solid states.ΔH,ΔS,ΔG and hydrogen isotope equilibrium pressures of the hydrogenating reactions have been calculated based on this approximation.The formation enthalpies for ZrCoH,ZrCoD and ZrCoT at temperature from 398 to 598 K are 82.81 ,81.54 and 80.49 kJ•mol－1 respectively.The results cohere with the experimental results.It means that the present method is somehow reasonable to theoretical study on thermodynamic functions of hydrogen storage materials.