First-principles study of the crystal structures and electronic properties of LaNi4.5M0.5 (MÂ =Â Al, Mn, Fe, Co)

► Al, Mn, Fe, Co atoms prefer to substitute Ni atoms in the 3g sites. ► LaNi4.5Mn0.5 alloy has the most stable structure among five systems. ► The interactions of Mn, Ni, Co and Ni atoms are stronger than the Ni-Ni interaction. ► H atoms mainly go through from the region of La-Ni (2c) atoms into the host alloy. ► LaNi4.5Mn0.5 has the best capacity of bounding hydrogen atoms among four systems.