First-principles investigations of the stability and electronic structure of ZrV2Hx (x=0.5, 1, 2, 3, 4, 6 and 7)

A calculation of the electronic structure and formation energy for ZrV2Hx (x = 0.5, 1, 2, 3, 4, 6 and 7) is performed using a plane-wave pseudo-potential method. It is found that in ZrV2Hx hydrogen forms stronger covalent bonds with vanadium than with zirconium if Zr atoms are in the neighborhood of V. A detailed analysis of how the densities of states change with the hydrogen count x in ZrV2Hx shows the changes in the bonding and anti-bonding interactions of H with V and Zr. However, the covalent anti-bonding interactions between H and V seem to be mainly responsible for the variation in the formation energy of ZrV2Hx with x. The value of projected density of states of V 3d at the Fermi level can be used as a rough comparative measure for these antibonding interactions and therefore allows us to predict the changes in stability of ZrV2Hx with x. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.