[ital Ab] [ital initio] calculation of melting and thermodynamic properties of crystal and liquid aluminum

Journal Article · Mon Aug 15 00:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.5055· OSTI ID:7007423

Straub, G K; Aidun, J B; Wills, J M; Sanchez-Castro, C R; Wallace, D C ^[1]

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1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

A first-principles technique for calculating accurate equations of state of metals is illustrated with an application to Al. Results for the thermodynamic properties of Al at densities near normal, and at temperatures into the liquid phase, are presented. In contrast to previous calculations by other workers, the present technique makes no use of experimental data. The [ital ab] [ital initio] procedure begins with electronic-band-structure calculation of the ground-state energy, the elastic constants, and selected short-wavelength phonons. A physically realistic interatomic potential is calibrated by fitting it to the calculated elastic constants and phonons. Ion-motional contributions are computed from quasiharmonic lattice dynamics at low temperatures, and from molecular-dynamics simulations at classical temperatures. Melting is computed from the free energy constructed from these combined results. Very accurate results are obtained for zero-temperature properties and phonon frequencies. The calculated melting temperature of 955 K is within 2.5% of the observed value, a difference comparable to the estimated precision of the calculation. Good results are obtained for two highly sensitive quantities, the entropy change upon melting and the Clapeyron slope. The calculated entropy as a function of temperature is in excellent agreement with experiment for solid and liquid phases. The present procedure can potentially provide reliable values of thermodynamic properties of any metal under extreme conditions where no data are avilable.

• OSTI ID: 7007423
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 50:8; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
EQUATIONS OF STATE
MELTING
METALS
BAND THEORY
ELECTRONIC STRUCTURE
ENTROPY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
ELEMENTS
EQUATIONS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
TEMPERATURE RANGE
THERMODYNAMIC PROPERTIES
360102* - Metals & Alloys- Structure & Phase Studies
360104 - Metals & Alloys- Physical Properties