Occupation of Hydrogen Atom in Intermetallic Compound θ-Al₂Cu:A First-Principles Calculation

When hydrogen atoms dissolved into θ-Al₂Cu unit cell, they could occupy octahedral interstitial site or tetrahedral interstitial sites.Influence of hydrogen dissolution on the θ-Al₂Cu unit cell structure, system total energy, formation energy, and Mulliken bond population and bond length between neighboring atoms in interstitial structures was analyzed by first-principles method.The tendency of hydrogen atoms occupying positions in θ-Al₂Cu was analyzed.The results show that when the hydrogen atom occupied the octahedral interstitial site, the system energy was the lowest, the formation energy was the smallest and negative, and the lattice distortion was the smallest; the bond population was positive and the bond lengths were the shortest between neighboring atoms, and the bond cooperation was the strongest.Therefore, when hydrogen atoms occupied θ-Al₂Cu octahedral interstitial site, the structure was more stable.