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Magnesiumhydride (MgH2) is considered a promising candidate as material forhydrogen storage due to its low cost, availability and non-toxicity, amongothers. However, the MgH2 activation energy for hydrogen kineticdesorption is relatively high [1]. One alternative for this inconvenient is theaddition of transition metals (TM) or defects like vacancies [2]. The goal ofthis study is to elucidate the chemical and physical changes by DFTcalculations due to Nb and charged vacancies incorporation in MgH2.Particularly, were considered an H vacancy (VH), or an Mg vacancy (VMg)or a di-vacancy H-Mg (VH-Mg) in MgH2 pure and MgH2+Nb.For each vacancy were taken into account three possible charge states (q = +1,0 and −1). The results show that the MgH2 doped with Nb has a bandgap reduction of around 68 % (from 3.79 eV to 1.20 eV), nevertheless thep-semiconductor behavior remains [3].Furthermore,the Nb induces a magnetic moment of 2.10 μB. Regarding to vacancy incorporation it can be seen that the changes more significant are inthe band gap zone, the valence and conduction band practically no change.Depending of charge states of them there is a band gap reduction and appears amagnetic moment. For example in pure MgH2 only the VMg+induces a magnetic moment (~0.79 μB), whereas in MgH2+Nb, is theonly one that no induces magnetism. Moreover, the VH in MgH2or MgH2+Nb generate additional states in the band gap zone. Forexample, this fact leads the system to semiconductor behavior for the spin upcontribution, and to a metallic behavior for the spin down contribution.Finally, it can be concluded from the results that both, the incorporation ofNb and charged vacancies, improve the H dissociation and conduce to interesting electronic properties.References1- Varin R., Czujko T., Wronski Z., Nanomaterials for SolidState Hydrogen Storage.Canada. Ed. Springer, Cap. 2 (2009).2- Yu R, Lam PK. Electronic and structural properties of MgH2.Phys Rev B1988;37:8730-7.3- S.Zh. Karazhanovabc, A.G. Ulyashinc , P. Vajeestona and P. Ravindrana.Hydrides as materials for semiconductor electronics. Philos. Mag. 2008;88:2461?2476.