  Hydrogen diffusion is critical to the performance of metals for hydrogen
storage as well as other important applications. As compared to its crystalline
counterpart which follows the Arrhenius relation, hydrogen diffusion in
amorphous metals sometimes are experimentally found to be non-Arrhenian. In
this work we studied the diffusion of hydrogen in amorphous Pd-H and Zr-Cu-H
alloys based on molecular dynamics simulations. Our simulations confirm
Arrhenian diffusion behaviour for hydrogen in amorphous alloys, in contrast to
previous theoretical studies which predict non-Arrhenian behaviour. We show
that the simulated non-Arrhenian diffusion based on molecular dynamics could
result from a systematic error related to too short simulation time. We also
discussed the experimental non-Arrhenian behaviour of hydrogen diffusion within
the framework of quantum tunneling and amorphous-amorphous phase
transformations.
