First-principles calculations to investigate the structural, electronic and lattice dynamical properties of the LaMgNi4Hx compounds for hydrogen storage applications (x = 0, 1, 4 and 7)

•Strutrual and electrinc properties of LaMgNi4, LaMgNi4H, LaMgNi4H7, and LaMgNi4H4 compounds have been investigated.•The structure of LaMgNi4, LaMgNi4H, and LaMgNi4H7 is cubic with the F-43 m space group.•LaMgNi4H4 is orthorhombic with space group Pmn21.•The band structures have been investigated using Full potential (FP).•The elastic anisotropy of these compounds have been investigated.•The phonon energy of these materials, were determined using the pseudo-potential (PP). and the full potential (FP)The thermodynamic properties of these compoundshave been investigated. This work is aimed at studing LaMgNi4 and its hydrides using the Functional Density Theory (DFT). We have found that these materials are stable through investigating their electronic, mechanical, and phonon properties. Two methods were used: Full Potential Linearize Augmented Plane Waves (FP-LAPW) and Plane Wave Pseudo Potential (PW-PP) to study the compounds LaMgNi4Hx with (x = 0, 1, 4 and 7) in both cubic and orthorhombic phases. The results of structural calculations using the exchange and correlation potential (WC-GGA) and comparison with other theoretical works in addition to some experimental results led us to report that these compounds have metallic behavior. The study of temperature influence on free energy, entropy, heat capacity, and the formation of enthalpies shows that these substances have good structural stability, we found that those materials are ductile. Despite that, we confirmed that these materials are thermodynamically and mechanically stable.