Electronic, structural, and mechanical properties of possible metastable phases of beryllium hydride

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.

Key Words:

• Beryllium hydride
• metastable
• high pressure
• pseudopotential method
• structural properties
• electronic structure.