Density functional theory study on (Mg(BH4))n (n=1-4) clusters as a material for hydrogen storage

Geometrical structures and relative stabilities of (Mg(BH4)(2))(n) (n = 1-4) clusters were investigated by B3LYP/6-31G** method. For the most stable isomers, the geometrical structures, vibrational spectra and B-H bond dissociation energies (BDEs) were further analyzed. Natural bond orbital (NBO) analysis was also performed. The structural analysis shows the average binding energies of (Mg(BH4)(2))(n) (n = 1-4) clusters are affected drastically by the structures of isomers and c3 structure is very close to the crystal structure. The spectroscopic analysis shows that the stretching vibrations of B-H bond close gradually with the augment of n value. In addition, the B-H bonds for singlet clusters are more stable that those for triplet clusters, which is proved by the analysis of gap energy (E-g) and high occupied orbital energy (E-Homo). (C) 2013 Elsevier B.V. All rights reserved.