Modulation of hydride formation energies in transition metal doped Mg by alteration of spin state

Coupled cluster and density functional theory calculations have been used to assess the role of the transition metal spin state upon the energetic favorability of hydride formation within small, transition metal doped, magnesium clusters. The spin state is found to modulate the occupation of bonding and anti-bonding orbitals, thus having a large effect upon both geometric and energetic parameters. This chemical description provides a potential theoretical basis for unexplained experimental observations, and indicates a mechanism for using an external magnetic field to control the thermodynamics of H2 sorption and desorption in metal hydrides.