Electronic structure and enthalpy of hydrogen and helium mixtures
The first local density approximation (LDA) calculations of the electronic structure, equation of state and enthalpy of mixing were carried out for a number of different compositions of hydrogen and helium in bcc and fcc lattices. These are fully quantum mechanical, self-consistent calculations utilizing state-of-the-art methods of electron band theory, which make no assumptions regarding pressure ionization. The major approximation in the LDA method is that the exchange and correlation energy is given by a free electron functional in terms of the local electron density. The majority of previous mixture calculations start with the assumption that both hydrogen and helium are pressure-ionized so that the electronic structure is approximately that of free or weakly screened electrons in the presence of positive ions. Stevenson used a hard-sphere mixture model for the ions with an ion-ion pseudopotential to account for electron screening and predicted that a mixture containing 7% helium by number, the composition believed to be present in Jupiter and Saturn, would phase separate at a temperature of about 7000 K at 8 Mbar. Subsequent calculations carried out for the fully ionized mixture and for a mixture of screened ions (linear response theory) have all arrived at predictions similar to those of Stevenson. MacFarlane and Hubbard performed ThomasFermi-Dirac calculations for mixing enthalpies of hydrogen and helium in bcc and fcc lattices and predicted that phase separation would not occur at any temperature.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 10157943
- Report Number(s):
- UCRL-JC-112346; CONF-9208135-7; ON: DE93014128
- Resource Relation:
- Conference: International conference on the physics of strongly coupled plasmas,Rochester, NY (United States),17-21 Aug 1992; Other Information: PBD: Nov 1992
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
HYDROGEN
ENTHALPY
HELIUM
THEORETICAL DATA
MIXTURES
ELECTRONIC STRUCTURE
EQUATIONS OF STATE
BCC LATTICES
FCC LATTICES
SELF-CONSISTENT FIELD
TEMPERATURE ZERO K
VERY HIGH PRESSURE
ENERGY-LEVEL DENSITY
METALS
PLANETARY ATMOSPHERES
SATURN PLANET
JUPITER PLANET
400201
360602
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES
STRUCTURE AND PHASE STUDIES