Molecular Dynamics Study on Hydrogen Diffusion in Palladium
Kenji NISHIMURA
Abstract:The characteristics of hydrogen diffusion in palladium such as the influences of temperature, hydrostatic pressure, pure shear, and lattice defect are investigated using molecular dynamics simulation. The simulations predict Arrhenius-type temperature dependence of the hydrogen diffusion in palladium. The diffusion activation energy is found to be 0.16 eV, in excellent agreement with value obtained by means of the first principle calculation. The calculated activation energy with zero-point energy corrections is consistent with reported experimental data. Furthermore, we find that the hydrogen diffusivity in palladium decreases with increasing the hydrostatic pressure in a system, especially this pressure dependence is larger in case of low temperature, and the pure shear applied to the system has little influence on the hydrogen diffusivity. In addition, the hydrogen diffusivity dramatically decreases with increasing defect density because the lattice defect acts as trap sites. Key Words:Molecular dynamics, Hydrogen diffusion, Palladium, Diffusivity, Temperature dependence, Activation energy, Pressure dependence