Theoretical investigations on low energy surfaces and nanowires of MgH2

The phase stability, chemical bonding, and electronic structure of MgH2 nanowires and possible low energy surfaces of alpha-MgH2 thin films have been investigated using the ab initio projected augmented plane-wave method. Structural optimizations based on total energy calculations predicted that, for the alpha-MgH2 phase, the (101) surface is more stable among the possible low energy surfaces. The electronic structure study reveals that the nanowires also have nonmetallic character similar to that of the bulk and thin film phases. Bonding analysis shows that the character of chemical bonding in nanowires has been considerably changed compared with that in bulk phases. Similarly, the bond distances in the surfaces of nanowires are found to be higher than in the bulk material, suggesting that it is possible to remove hydrogen from the nanowires considerably more easily than from bulk crystals.