Abstract: 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 .

Key words: Zr, ZrH, Molecule structure, Thermodynamic function