Electronic structure and bonding of the hydrides Mg3TH7 (T = Mn, Re) from first principles
Résumé
From pseudo-potentials and all-electrons computations within density functional theory, desorption energies within range of MgH2 and covalent like hydrogenated intermetallic compounds are identified for hydrogen rich Mg3TH7, (T = Mn, Re). The rhenium based compound is found with a lower desorption energy which has been quantified from the analysis of the Bader charges within the {TH6}5- complex anion as related with a decreasingly ionic charge on hydrogen from Mn to Re. The electronic densities of states show insulating compounds in agreement with literature relevant to this class of salt-like hydrides with a larger band gap for the Re compound. From chemical bonding analyses stronger Mn-H bonding versus Re-H is identified in agreement with desorption energies magnitudes favoring Mg3ReH7.