The Effect of Rare Earth Elements on Structural, Electronic, and Storage Properties for RNi5H6 Intermetallic Hydrides under Stress

All calculations in hand have been investigated by using the first-principles method within the full-potential linearized augmented plane wave (FP-LAPW) method implemented in wien2k package. The framework of generalized gradient approximation (GGA96) has been used to describe the exchange-correlation potential. It has been found that the substitution and the increase of pressure cause a decrease in the bond length, lattice constant, and volume. Noticeably, the energetic properties are improved after applied pressure variations and the substitution, such as after the substitution of La with Y and Sc the heat of formation value reduces by about 20 and 10%, respectively. Otherwise, the gravimetric hydrogen storage (wt %) is increased after the substitution. Furthermore, the pressure variations and the substitution led to the Fermi energy value increased and the density of states at the Fermi level decreased.