HR: 1340h
AN: MR23A-0045    [Abstracts]
TI: High-to-low spin transition in magnesiumwustite under pressure
AU: * Tsuchiya, T
EM: takut@sci.ehime-u.ac.jp
AF: Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, 790-8577 Japan
AU: Wentzcovitch, R M
EM: wentzcov@cems.umn.edu
AF: Department of Chemical Engineering and Materials Science, Minnesota Supercomputing Institute for Digital Technology and Advanced Computations, University of Minnesota, 421 Washington Av SE, Minneapolis, MN 55455 United States
AU: de Gironcoli, S
EM: degironc@sissa.it
AF: Scuola Internazionale Superiore di Studi Avanzati and DEMOCRITOS National Simulation Center, via Beirut 4, Trieste, 34014 Italy
AB: High resolution X-ray spectroscopy has recently demonstrated that iron in the major lower mantle (LM) minerals undergo a high-to-low spin transition at LM pressures (23-135 GPa). Previous failures of standard DFT and "LDA+U" approaches to describe this phenomenon have hindered its investigation and consequences of fundamental importance to geophysics, such as heat transport in Earth's mantle. Here, using the latest rotationally invariant first principles formulation of LDA+U with optimized effective U, we report the first successful study of this transition in low solute concentration (Mg_1-xFE_x)O, magnesiumwustite. This is believed to be the second most abundant phase of Earth's LM. This encouraging result appears to open for exploration a new class of problems of enormous significance to deep Earth geophysics. Research supported by JSPS, NSF/ITR 0428774, VLab, Ehime U Project Fund
DE: 3620 Mineral and crystal chemistry (1042)
DE: 3900 MINERAL PHYSICS
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3939 Physical thermodynamics
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005