Abstract
We have studied the electronic, structural, and mechanical properties of two possible metastable phases of beryllium dihydride, BeH2, using total energy calculations based on the self-consistent, ob-initio pseudopotential method. The two investigated structures are the fluorite structure and the calcium carbide structure. The minimum-energy volumes per BeH2 are found to be smaller for both structures than the volume per BeH2 for the observed stable structure. As a result, the hydrogen density is greater for both investigated structures than for the observed BeH2 phase. In addition, both phases are predicted to be semimetals with ionic bonding between the negatively-charged hydrogen ions and the positively-charged beryllium ions. The bulk modulus for the fluorite structure is three times larger than the one for the calcium carbide structure.