High pressure polyhydrides of molybdenum: A first-principles study

We present results from first-principles calculations on molybdenum polyhydrides under pressure. In addition to the experimental epsilon-phase of MoH, we find several novel structures of MoH2 and MoH3 at pressures below 100 GPa. A hexagonal structure of MoH2 becomes stable with respect to decomposition into MoH and H-2 above 9 GPa, and transforms into an orthorhombic structure at 24 GPa, which remains stable up to 100 GPa. MoH3 is unstable relative to decomposition into MoH and H-2 over the whole pressure range studied. Electronic structure calculations reveal that molybdenum polyhydrides are metallic under pressure. (C) 2016 Elsevier Ltd. All rights reserved.