  We employ two different atomistic methods to investigate solute-defect
interactions in nanosized palladium-hydrogen (Pd-H) systems across multiple
time scales. The first method, referred to as Diffusive Molecular Dynamics
(DMD), focuses on capturing hydride phase transformation and the evolution of
solute-induced lattice defects over a diffusive time scale. The second method,
Molecular Dynamics (MD), provides more detailed insights into atomic movements
and lattice relaxation over the time scale of thermal vibrations. These two
methods are connected with MD simulations initialized using statistical
measures of microscopic variables obtained from DMD at different H/Pd ratios.
Our study demonstrates that DMD effectively captures the propagation of an
atomistically sharp hydride phase boundary as well as the dynamics of
solute-induced misfit dislocations and stacking faults. While the
H-concentrated phase leads to a reduction in the vibrational energy, the
presence of stacking faults locally increases the vibrational energy of both Pd
and H atoms. Furthermore, the MD simulation results align with DMD in terms of
equilibrium potential energy, the preservation of hydride phase boundary, and
the spatial distribution of stacking faults. We thoroughly characterize the
lattice crystalline structures in four key regions of the particle. We observe
a preference for H atoms to occupy tetrahedral interstitial sites near stacking
faults due to the lower stacking fault energies provided by these sites within
the H-concentrated phase.
