Comparison of metal additives and Boron atom on MgH2 absorbing-desorbing characteristics using calculated NQCCs

Using ab initio calculations, the hydrogen desorption from Magnesium hydride (MgH2) was studied. We presented the calculated nuclear quadrupole coupling constants (NQCCs) of hydrogen atom in various systems of MgH2. The effect of interactions of some metal atoms as well as Boron atom with MgH2 host matrix; (MgH2+M) nanostructures (M=Al, Ti, V, Fe, Ni and B); were studied and 2H-NQCCs were calculated. From results, introduction of B decreased 2H-NQCC and consequently trend of decrease of charge density in the presence of B was observed. In the other hands introduction of B destabilized initial structure of MgH2, But in (MgH2+M) nanostructures(M=Al, Ti, V, Fe and Ni) the 2H- NQCCs were larger than those of pure MgH2 and consequently more difficult condition for hydrogen desorption were created. However at sufficiently low B concentration (Mg15BH32); the calculation predicted existence of stable dopant system with greater 2H-NQCC.The electric field gradient (EFG) at the site of quadrupolar nuclei were calculated to obtain NQCC parameters at HF/3-21G level of theory.