Quantmn Mechanical Calculation of the Adsorption of Hydrogen Isotopes on Metallic Cobalt

The thermodynamic functions for the hydrogenating of metal or alloy are very important for hydrogen storage material design. Density functional (B3LYP/SDD) method with Relativistic Effective Core Potential (RECP) have been used to optimize the structure, and to calculate energy E, entropy S and enthalpy H of CoH (D,T). The multiply of the ground state CoH is three, and Re, D 0, ωe are 0.152 nm, 277.84 kJ/mol and 1321 cm-1 respectively, these parameters are agreement with the experimental ones. Considering the characteristics of different motion types, the electronic and vibration energy or entropy of the molecules are assumed to be the corresponding values of their solid states.ΔH , ΔS , ΔG and hydrogen equilibrium pressure of the hydrogenating reaction have been calculated based on this approximation and very obvious isotope effects have been observed. The results show that the present method is reasonable to theoretical study on the thermodynamic functions of hydrogen-storage materials.