This work presents an in-depth analysis of the structural, hydrogen storage, phonon, electronic, optical, me chanical, and thermodynamic properties of MgA Aʹ H6 (A =Li, Na; Aʹ =Co, Rh, Ir), employing density functional theory (DFT) in a pioneering study. Structural investigation verifies that the examined hydrides are stable within a cubic crystal structure belonging to the F 43 m (#216) space group. The calculated gravimetric hydrogen storage capacities are 6.29 wt%, 5.39 wt%, 3.87 wt%, and 2.46 wt% for MgLiCoH6, MgNaCoH6, MgNaRhH6, and MgNaIrH6, respectively. Phonon dispersion curves validate dynamic stability, while Ab initio molecular dynamics (AIMD) simulations indicate thermal stability with no structural deformation. Electronic structure calculations reveal semiconducting properties, with MgLiCoH6 and MgNaCoH6 exhibit direct band gaps, whereas MgNaRhH6 and MgNaIrH6 represent indirect band gaps. The hydrides studied primarily absorbing the quanta of energy in the ultra-violet region of the spectra. The elastic constants were calculated, affirming the mechanical stability of all the hydrides investigated. Also computed mechanical characteristics indicate that all examined hydrides exhibit elastic anisotropy and brittleness. The thermodynamic parameters, including entropy, heat capacity, energy, and free energy, were followed up and found to comply with the laws of thermodynamics. The present DFT results indicate that MgLiCoH6 and MgNaCoH6 hydrides possess significant promise as candidates for hydrogen storage applications.

Title

International Journal of Hydrogen Energy

Publisher

ELSEVIER

Publisher Country

United Kingdom

Indexing

Thomson Reuters

Impact Factor

8.3

Publication Type

Both (Printed and Online)

Volume

223

Year

2026

Pages

15