HR: 0830h
AN: V51A-10    [Abstracts]
TI: Lattice dynamics and thermodynamics of hexagonal-close-packed iron at high temperatures and pressures
AU: * sha, x
EM: x.sha@gl.ciw.edu
AF: Geophisical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd., N. W., Washington, DC 20015-1305 United States
AU: Cohen, R E
EM: cohen@gl.ciw.edu
AF: Geophisical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd., N. W., Washington, DC 20015-1305 United States
AB: We performed linear-response Linear-Muffin-Tin-Orbital (LMTO) calculations to understand and predict the lattice dynamical and thermal properties of hexagonal-close-packed iron at high temperatures and pressures. The phonon dispersion and phonon density of states have been calculated at different volumes and various c/a axial ratios, which show good agreements with available experimental data. We also calculated the thermal conductivity and electrical resistivity at different pressure. We derived the Hemlmholtz free energy functionals based on the LMTO calculations, and have further applied to establish the thermal equation of state, bulk modulus K0, dK0/dT, and thermal expansion coefficients at high pressures and temperatures. The variations of c/a ratios with temperature and pressure have been predicted. We also used the particle-in-cell approach to examine the thermal properties based on tight-binding total energy calculations, and made a detailed comparison with lattice dynamics calculations and experiment. The influence of anharmonic effects has been examined. This work was supported by US Department of Energy ASCI/ASAP subcontract to Caltech, Grant DOE W-7405-ENG-48 (to REC).
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3939 Physical thermodynamics
DE: 3949 Thermal expansivity
DE: 5139 Transport properties
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2005 Joint Assembly