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Physics of the Earth and Planetary Interiors 155 (2006) 260268 Phase stability of CaSiO3 perovskite at high pressure and

Summary: Physics of the Earth and Planetary Interiors 155 (2006) 260­268
Phase stability of CaSiO3 perovskite at high pressure and
temperature: Insights from ab initio molecular dynamics
Li Lia,b,, Donald J. Weidnera,b, John Brodholta, Dario Alf`ea, G. David Pricea,
Razvan Caracasc, Renata Wentzcovitchc
a Department of Earth Sciences, University College London, Gower Street, London WC1E6BT, UK
b Mineral Physics Institute, Department of Geosciences, University of New York at Stony Brook, Stony Brook, NY 11790, USA
c Department of Chemical Engineering and Material Science, Minnesota Supercomputing Institute,
University of Minnesota, Minneapolis, MN 55455, USA
Received 7 September 2005; received in revised form 2 December 2005; accepted 20 December 2005
We report the dynamics of the structure of CaSiO3 perovskite from ab initio molecular dynamics (AIMD) calculations at high
pressure (P up to 130 GPa) and high temperature (T up to 5000 K). Our calculations indicate three separate stability fields: orthorhom-
bic, tetragonal and cubic, with the tetragonal phase dominating the pressure and temperature region between room temperature and
4000 K. These regions are defined by the stress symmetry of the AIMD calculation. The boundary between the orthorhombic
and the tetragonal structures is found to have a positive Clapyron slope and is close to room temperature at low pressure. The
boundary is marked by the transition from stable, constant octahedral tilts, to dynamically varying tilts that change sign with time.
The calculated atom positions indicate that the orientation of the octahedra can be noted as a-


Source: Alfè, Dario - Departments of Earth Sciences & Physics and Astronomy, University College London


Collections: Physics; Geosciences