Structural, mechanical and electronic properties of transition metal hydrides MH2 (M = Ti, Zr, Hf, Sc, Y, La, V and Cr)

First-principles calculations have been carried out to investigate the structural, mechanic and electronic of transition metal hydrides MH2 (M = Ti, Zr, Hf, Sc, Y, La, V and Cr). It is found that TiH2 is mechanically unstable because of a negative C44 = −21.31 GPa and C11–C12 < 0, the same behavior can be found in MH2 (M = Zr, Hf, and Y) compounds. Also there is a strong interaction between M (Ti, Zr, Hf, Sc, Y, La, V and Cr) and H. On the other hand, the H–H bond orders are always negative or nil reason of brittleness.

Graphical abstractPartial state densities for MH2 (Ti, Zr, Hf, Sc, Y, La, V and Cr) structures .Figure optionsDownload full-size imageDownload as PowerPoint slide