First-Principles Investigations of the Electronic Structure of B -Lani4alhx (X=4, 4.5, 5, 7)

The electronic structures of β -LaNi₄AlH_x (x=4, 4.5, 5, 7) have been investigated using a plane- wave pseudo-potential method. The results of calculated formation energy and equilibrium unit cell volume show that LaNi₄AlH_4.5 is the most favorable structure to the real composition of LaNi₄AlH_x. LaNi₄AlH₇ should not be formed as a stable hydride due to the reduction in the number of H-Ni bonding states associated with the reduction in the number of d states near the Fermi surface in LaNi₄AlH₇. LaNi₄Al can not absorb hydrogen as much as LaNi₅.