Effect of H-atom on local structure in Ni-Zr-NbAmorphous alloy

We optimize the atomic structures of icosahedral Ni₆Zr₅Nb₃ with an added H-atom in a periodic cell as a local structural model of Ni-Zr-Nb-H amorphous alloys by the first principles calculation, and identify energetically favorable H-atom sites in the local structure of the amorphous alloys. We find that a H-atom is favorably located not at tetrahedral sites in the icosahedral cluster but at octahedral sites in the region of inter-cluster. We also find that a H-atom in some tetrahedral sites induces a rearrangement of the local structure from icosahedral to fcc-like, which seems to correspond to a local crystallization in the amorphous phase. These results give a fundamental behavior of hydrogen atoms in Ni-Zr-Nb amorphous alloys and information to elucidate the mechanism of the electrical transport in the Ni-Zr-Nb amorphous alloys with H-atoms.