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Title: Metallization and superconductivity of BeH{sub 2} under high pressure

Pressure-induced metallization and potential superconductivity of BeH{sub 2} has been a topic of interest. In the present study, we extensively explored the crystal structures of BeH{sub 2} in a wide pressure range of 0–300 GPa using an unbiased structure searching method coupled with first-principles density functional calculations. A series of pressure-induced structural transformations are predicted for BeH{sub 2}, as Ibam (α phase) → P-3m1 (phase II) → R-3m (phase III) → Cmcm (phase IV). Calculated pressures of phase transition are 25, 140, and 202 GPa, respectively. The phase II is isostructural to the well-known 1T structure of transition metal dichalcogenides, which is composed of covalent bonded BeH{sub 2} slabs stacked along the perpendicular direction by van der Waals forces. The phase III is constructed by the same BeH{sub 2} slabs, but differs from the phase II in the stacking sequence. The α phase, phase II, and phase III all have insulating electronic states while their band gaps decrease as pressure increases. We predicted that BeH{sub 2} reaches a metallic state by a III → IV phase transition, instead of a direct band gap closure in phase III. The phase IV has a three-dimensional extended Be-H network formed by edge-sharing BeH{submore » 8} polyhedrons with delocalized electrons. Electron-phonon coupling calculations implemented using linear response theory on the metallic BeH{sub 2} predict a large electron-phonon coupling parameter of 0.63, leading to an estimation of superconducting transition temperature (T{sub c}) of ∼38 K at 250 GPa.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [2] ;  [4]
  1. State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China)
  2. Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada)
  3. (Canada)
  4. Computational Astrophysics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
Publication Date:
OSTI Identifier:
22253383
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 12; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BERYLLIUM HYDRIDES; DENSITY FUNCTIONAL METHOD; ELECTRON-PHONON COUPLING; ORTHORHOMBIC LATTICES; PHASE TRANSFORMATIONS; PRESSURE RANGE GIGA PA; PRESSURE RANGE MEGA PA 10-100; SLABS; SUPERCONDUCTIVITY; TRANSITION ELEMENTS; VAN DER WAALS FORCES