Abstract: 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.

Key words: ZrCo, ZrCoH, Molecule structure, Thermodynamic function, Ab initio