Ab initio calculations of MgH 2 , MgH 2 :Ti and MgH 2 :Co compounds

abstract The understanding of hydrogen bonding in magnesium and magnesium based alloys is animportant step toward its prospective use. In the present study, a density functional theory(DFT) based, full-potential augmented plane waves method of calculation, extended withlocal orbitals (FP-APWþlo), was used to investigate the stability of MgH 2 and MgH 2 :TM(TM¼Ti and Co) 10 wt % alloys and the influence of this alloying on hydrogen storageproperties of MgH 2 compound. Effects of a possible spin polarisation induced in the systemby transition metal (TM) ions were considered too. It has been found that TM-H bonding isstronger than the Mg–H bond, but at the same time it weakens other bonds in the secondand third coordination around a TM atom, which leads to overall destabilization of thecompound. Due to a higher number of d-electrons, this effect is more pronounced forCo alloying, where in addition, the spin polarisation has a noticeable and stabilisinginfluence on the compound structure.a 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.