First principles study of structural, electronic and mechanical properties of transition metal hydrides (TMH, TM=Mo, Tc, Ru)

The structural, electronic and mechanical properties of transition metal hydrides (TMH, TM=Mo, Tc, Ru) are investigated by means of first principles calculation based on density functional theory with generalized gradient approximation. Among the five crystallographic structures that have been investigated, the cubic phase is found to be more stable than the hexagonal ones. A structural phase transition from ZB to WC in MoH, NaCl to NiAs in TcH and NaCl to ZB to NiAs in RuH is also predicted under high pressure. The calculated elastic constants indicate that all the three hydrides are mechanically stable at ambient pressure.