HR: 1340h
AN: MR23C-1526    [Abstracts]
TI: Metadynamics study of iron phases at the Earth's inner core conditions
AU: * Zhang, F
EM: feiwu.zhang@mat.ethz.ch
AF: ETH Zurich, Switzerland, Lab. of Crystallography, Department of Materials, Wolfgang-Pauli-Strasse 10, Zurich, CH-8093, Switzerland
AU: Oganov, A R
EM: artem.oganov@mat.ethz.ch
AF: ETH Zurich, Switzerland, Lab. of Crystallography, Department of Materials, Wolfgang-Pauli-Strasse 10, Zurich, CH-8093, Switzerland
AB: Iron is the main element in the Earth core and the stable phase of iron in the Earth's solid inner core is still highly controversial (Sambridge, 2003). In order to predict the properties of iron at high pressures and temperatures, here, we use a novel simulation technique, first-principles metadynamics (Martonak et al., 2003, see also Oganov et al., 2005 ), to unveil the stepwise mechanism of the pressure-induced (350 GPa) transformations between bcc, fcc and hcp iron at the temperatures of 2000 K and 6000 K respectively. We predicted the bcc \{110\}, fcc \{111\} and hcp \{111\} slip planes at the Earth inner core conditions. We also predicted some metastable iron phases (e.g. R-3M and P-6M2 structures) on the pathway of the phase transition. The c/a ratios of the iron structures are also calculated at the simulated conditions. Implications of these results for seismic anisotropy in the Earth inner core will be discussed (Zhang, 2007). References: [1] Sambridge M., (2003) An Ensemble View of Earth's Inner Core. Science, 299, 529-530; [2] Martonak R., Laio A., and Parrinello M., (2003). Predicting crystal structures: The Parrinello-Rahman method revisited. Phys. Rev. Lett. 90, 075503; [3] Oganov A.R., Martonak R., Laio A., Raiteri P., Parrinello M. (2005). Anisotropy of Earth's D" layer and stacking faults in the MgSiO3 post-perovskite phase. Nature 438, 1142-1144; [4] Zhang F. & Oganov A.R., (2007) Metadynamics study of iron phases at the Earth's inner core conditions. (in prep.)
UR: http://olivine.ethz.ch/~feiwu/07AGU.html
DE: 0520 Data analysis: algorithms and implementation
DE: 0545 Modeling (4255)
DE: 3620 Mineral and crystal chemistry (1042)
DE: 3994 Instruments and techniques
DE: 5460 Physical properties of materials
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting