A First-Principles Multi-phase Equation of State of Carbon under Extreme Conditions
We describe the construction of a multi-phase equation of state for carbon at extreme pressures based on ab initio electronic structure calculations of two solid phases (diamond and BC8) and the liquid. Solid-phase free energies are built from knowledge of the cold curves and phonon calculations, together with direct ab initio molecular dynamics calculations of the equation of state, which are used to extract anharmonic corrections to the phonon free energy. The liquid free energy is constructed based on results from molecular dynamics calculations and constraints determined from previously calculated melting curves, assuming a simple solid-like free energy model. The resulting equation of state is extended to extreme densities and temperatures with a Thomas Fermi-based free energy model. Comparisons to available experimental results 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:
- 946946
- Report Number(s):
- LLNL-JRNL-401075; TRN: US0901289
- Journal Information:
- Physical Review B, na, na, July 1, 2008, pp. 024101, Journal Name: Physical Review B, na, na, July 1, 2008, pp. 024101
- Country of Publication:
- United States
- Language:
- English
Similar Records
[ital Ab] [ital initio] calculation of melting and thermodynamic properties of crystal and liquid aluminum
Carbon under extreme conditions: Phase boundaries and electronic properties from first-principles theory