LaNi_(4.5)Ga_(0.5)-H的电子结构和氢原子微观组态

The Electronic Structure and Hydrogen Microarrangements of LaNi_(4.5)Ga_(0.5)-H Systems

采用全势线性缀加平面波(FP-LAPW)方法研究了LaNi4.5Ga0.5Hy(y=1.0,1.5)的晶体结构,电子结构和氢原子的微观组态.计算基于H-H间的距离不小于2.1的准则,采用结构优化和内坐标驰豫并通过计算氢原子占据不同格位时LaNi4.5Ga0.5Hy的总能量得出氢原子最可能占据的位置.研究发现氢原子优先占据6m,12n*和3f位,4h格位没有氢原子占据.由于晶胞膨胀导致Ni-d带变窄,Ga原子的加入引起费米能级处态密度的降低,H原子的作用则相反.H和Ni,Ga之间的相互作用是LaNi4.5Ga0.5Hy固溶体保持稳定的主要因素.费米能级EF向高能区域移动的越少体系越稳定.

The crystal structures, electronic structures and hydrogen occupatied sites of LaNi4.5Ga0.5Hy （y = 1.0, 1.5） have been investigated using all-electron FP-LAPW method. Their equilibrium structures have been determined based on cupation sites in LaNi4.5Ga0.5Hy and the rule of H-H the calculated relative stabilities of hydrogen ocseparation to be no less than 2.1 A, as well as the full optimization. The hydrogen atoms were found to prefer the 6m, 12n^＊ and 3f sites. A narrowed Ni-d band was found due to the lattice expansion. The Ga atom leads to a decrease of n（EF）, while the H atoms do the opposite. The interaction between Ga and Ni, H plays a dominant role in the stability of LaNi4.5Ga0.5Hy. The smaller the shift of Er towards higher energy region is, the more stable will be the compounds.