THE ELECTRONIC AND MAGNETIC STRUCTURES OF TMAl5H12 SYSTEMS

This study presents an ab initio investigation of the interaction of Al5H12 with the alloying transition elements (TM) in the TMAl5H12 (TM = Ti, V, Fe, Co and Ni). Hydrogen atoms are found to prefer the tetrahedral sites in the fcc Al bulk system with a binding energy that is more energetically favored than octahedral sites by 0.17 eV. Absorbed H atoms in Al increase the lattice constant and decrease the cohesive energy by 13.8% and 32.7%, respectively. The present values of the H–H bond length (0.75 Å) and the dissociation energy of H2 (4.47 eV) are in good agreement with the previously measured values. The binding energy of H atoms in TiAl5H12 system is higher than the other studied systems due to the hybridization between s-state of H and d-state of Ti atom. The magnetic moments of Fe in FeAl5H12 system and Ni in NiAl5H12 system are enhanced as compared to the dehydrogenated system.