Electronic and structural properties ofMgH2

The electronic and structural properties of ${\mathrm{MgH}}_2$ are calculated using an ab initio pseudopotential method. The calculated quantities are the equilibrium structural parameters, the cohesive energy, a few selected elastic constants, the bulk modulus, the phonon frequency of a zone-center optical mode involving hydrogen vibration, the energy-band structure, the density of states, and the electronic charge distribution. The structural parameters and the cohesive energy are in good agreement with experiments. No comparisons are made for the other calculated properties because of the lack of experimental values. The bonding nature of ${\mathrm{MgH}}_2$ is interpreted in terms of the band structure and the charge distribution. Covalent bonding was not found, in contrast to previous suggestions that it exists in ${\mathrm{MgH}}_2$. Based on our band-structure and charge-density results, we suggest that ${\mathrm{MgH}}_2$ doped with a monovalent element could be a superconductor.