Calculations of High-Pressure Properties of Beryllium: Construction of a Multiphase Equation of State
We describe the construction of a three-phase equation of state (EOS) for elemental beryllium. The phases considered are: the ambient hcp phase, the high-temperature bcc phase, and the liquid. The free energies of the solid phases are constructed from cold, ion-thermal, and electron-thermal components derived from ab initio electronic structure-based calculations. We find that the bcc phase is unstable near ambient conditions, and that even at high pressures at which the bcc phase is stable, the bcc-hcp energy barrier can be as small as a few hundred Kelvins. The liquid free energy is based on a model of Chisolm and Wallace and is constrained by using the melt curve (determined by ab initio 2-phase simulations) as a reference. The high-temperature plasma limit is addressed with an average-atom-in-jellium model. Comparisons to experimental results, both for the ambient hcp phase, and for the phase diagram as a whole, are discussed.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 957187
- Report Number(s):
- LLNL-JRNL-405796; TRN: US1002297
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 79; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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