Lanthanum hexahydrometallates as promising candidates for hydrogen storage and optoelectronic devices, based on DFT analysis

Density functional theory (DFT) approach is used to calculate the thermodynamic, structural, mechanical, electronic, and gravimetric hydrogen storage capacities (GHSCs) and optical properties of LaXH 6 (X[Formula: see text] [Formula: see text] [Formula: see text]Al, In, Ga and B) hydrides for their potential applications in renewable energy sources. The lanthanum hexahydrometallates, LaXH 6 (X[Formula: see text] [Formula: see text] [Formula: see text]Al, In, Ga and B) have shown great potential for hydrogen storage, with impressive GHSCs values of 3.52, 2.33, 2.82 and 3.89[Formula: see text]wt.% for LaAlH 6 , LaInH 6 , LaGaH 6 and LaBH 6 , respectively. The measured values of energy band gaps for LaXH 6 (X[Formula: see text] [Formula: see text] [Formula: see text]Al, In, Ga and B) hydrides in spin-up channels are 2.249, 2.063, 1.447 and 0.539[Formula: see text]eV, respectively, while band gaps for spin-down channels are 2.247, 2.060, 1.449 and 0.541[Formula: see text]eV, respectively. These indirect band gaps show that they are semiconductor materials and are suitable for optoelectronic devices. Optical parameters such as optical conductivity (2.5–4.5[Formula: see text]fs[Formula: see text]), dielectric function (1.5–3.5), absorption (10 5 [Formula: see text]cm[Formula: see text]) and refractive index (1.5–3) peaks lie in the visible to near UV regions. Additionally, the Density Functional Perturbation Theory (DFPT) method is employed to investigate thermodynamic properties, the zero-point energies of LaXH 6 (where X[Formula: see text] [Formula: see text] [Formula: see text]Al, In, Ga and B) hydrides are 1.1799, 1.1580, 1.1074 and 0.9526[Formula: see text]eV, respectively, and the variation in zero-point energies shows that these compounds can significantly alter bond strengths and atomic interactions. XRD analysis reveals a distinct characteristic peak at 27.4 ∘ confirming the trigonal symmetry with the R3m space group. The XY, YZ and XZ directions show anisotropic behavior for the mechanical properties of the hydrides; their mechanical properties ([Formula: see text]) show that they are ductile and appropriate for next-generation hydrogen storage and optoelectronic applications.