Atomistic Simulation of Hydrogen-Defect Interactions in Palladium Nanoparticles Across Multiple Time Scales

This paper aims to explore solute-defect interactions in nanosized palladium-hydrogen (Pd-H) systems across multiple time scales through two atomistic methods. The first method, namely Diffusive Molecular DynamicsMolecular dynamics (MD) (DMD), is capable of capturing the mass transport of H atoms and the dynamics of solute-induced latticeLattices defectsDefects over a long diffusive time scale. The second one, Molecular Dynamics (MD)Molecular dynamics (MD), aims to provide more detailed information into instantaneous atomic movements and hopping over the time scale of thermal vibrations. These two methods are connected by initializing MDMolecular dynamics (MD) simulations with statistical measures of microscopic variables that are obtained from DMD at different H/Pd ratios. Our simulation results show that DMD is able to capture the motion of an atomistically sharp hydride phase boundary as well as the initialization and dynamics of solute-induced latticeLattices defectsDefects, i.e., misfit dislocations and stacking faults. While the H-rich phase leadsLead to an increase in the vibrational standard deviation of Pd and H atoms, the existence of stacking faults locally reduces it. Furthermore, the MDMolecular dynamics (MD) simulation results match well with DMD ones in terms of the equilibrium potential energy, the preservation of hydride phase boundary, and the spatial distribution of stacking faults.