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LINUX Cluster Project

Solid Solution and Miscibility of Technical Carbide Systems


Institution

  • Name: Universität Bayreuth;Bayerisches Geoinstitut
  • Address: Universitätsstraße 30, 95447 Bayreuth
  • Project Proposal Date: 2018-04-12 08:24:12

Abstract:

First-principles (FP) computations on physical properties of Earth materials under high pressure provide valuable information on the properties of Earth?s interior under high pressure. Computations based on density functional theory (DFT) provide ease in access to information on physical properties that are difficult to measure experimentally in the laboratory. Such studies on the properties of Mg- and Al-bearing silicates and oxides did obtain good agreement with experiments and hence inherent predictive power [e.g. 1-3]. However, inherent discrepancies exist in experiments for Al-bearing perovskite [e.g. 4,5] that is the most important phase in the Earth?s lower mantle [6]. These could be caused by incorporation of noble gases in diamond anvil cell experiments where they are used as pressure transmitting media. Such behavior would also be of great geochemical significance as the incorporation of noble gases in the Earth in such a phase would provide an explanation for the ?missing noble gases? such as Xenon. Here we explore the incorporation of noble gases into the perovskite phase by means of DFT-based computations to address the following x questions: (1) Can the oxygen vacancy incorporation mechanism (ovm) [7] of Al into the perovskite phase create a host place for a noble gas, and what is the energetics of such a substitution? (2) Is the compression behavior of the noble-gas bearing perovskite significantly different from a simple ovm substitution and a charge-coupled substitution? (3) How do the noble gases (He, Ne, Ar, Kr, Xe) affect the compression behavior differently? For these tasks we will rely on community-developed software, specifically the software package VASP [8] that is well maintained at LRZ. We have a license to this code in our working group. [1] A. R. Oganov, M. J. Gillan, and G. D. Price, J. Chem. Phys., 118, 10174 (2003). [2] F. C. Marton and R. E. Cohen, Am. Mineral., 79, 789 (1994). [3] B. B. Karki, L. Stixrude, and R. M. Wentzcovitch, Rev. Geophys. 39, 507 (2001). [4] T. Yagi, K. Okabe, N. Nishiyama, A. Kubo, and T. Kikegawa, Phys. Earth Planet. Inter. 143?144, 81 (2004). [5] D. Andrault, N. Bolfan-Casanova, M.A. Bouhifd, N. Guignot, and T. Kawamoto, Earth Planet. Sci. Lett. 263, 167 (2007). [6] D. J. Frost, Elements 4, 171 (2008). [7] S. Akber-Knutson, G. Steinle-Neumann, and P. Asimow, Geophys. Res. Lett. 32, L14303 (2005). [8] www.vasp.at