EHMO Cluster calculations on hyperstoichiometric Laves phase alloys and hydrides

Extended Huckel molecular orbital (EHMO) cluster calculation has been performed on zirconium containing hyperstoichiometric ZrB2+x (where B → 3d transition metal atom) hydrogen storage alloys to examine the preferential position of B atoms corresponding to hyperstoichiometry. Binding energies of clusters indicate tetrahedral sites as the preferential site for occupation by excess B atoms. Among the available sites hydrogen prefers to occupy A2B2 sites with partial negative charge. Energy values show the order of stability of the hydrides to be ZrV2>ZrMn2>ZrCr2.