Metallization and superconductivity of BeH2 under high pressure

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Beryllium hydride (BeH2) is of interest for its potential metallization and superconductivity under pressure.
• Understanding pressure-induced structural and electronic changes is crucial for discovering new materials with unique properties.

Purpose of the Study:

• To explore the crystal structures of BeH2 under high pressure (0-300 GPa).
• To investigate the pressure-induced metallization and potential superconductivity of BeH2.

Main Methods:

• Employed an unbiased structure searching method combined with first-principles density functional calculations.
• Utilized linear response theory to calculate electron-phonon coupling and superconducting transition temperature.

Main Results:

• Predicted a series of pressure-induced structural transformations: Ibam (α) → P-3m1 (II) → R-3m (III) → Cmcm (IV) at 25, 140, and 202 GPa.
• Identified metallization occurring at the III → IV phase transition, not through direct band gap closure.
• Calculated a large electron-phonon coupling parameter (0.63) for metallic BeH2, predicting a superconducting transition temperature (Tc) of ~38 K at 250 GPa.

Conclusions:

• Beryllium hydride undergoes significant structural changes under pressure, leading to a metallic state.
• The predicted high superconducting transition temperature suggests BeH2 as a promising candidate for high-pressure superconductors.