High-pressure phase diagrams of (a) MgO, (b) , (c) . (a) Theoretical results of Oganov et al. [black line with solid circles (Ref. 48)] and Strachan et al. [gray lines (Ref. 49)], (b) Theory [solid lines with circles (Ref. 27)], experiment [solid lines (Refs. 22 and 23)], interpretation of shock-wave data [dashed lines (Ref. 50)], (c) Theory (Ref. 5) and experiment [circles (Ref. 51), squares (Ref. 5)]. Adapted from Refs. 5, 27, and 48.
Phonon dispersion curves of perovskite (a) at , (b) at . , , , , , , . ( setting).
Phonon dispersion curves of polymorphs: (a) stishovite at , (b) -type phase at , (c) type phase at , (d) type phase at (e) pyrite-type phase at . Stishovite: , , , , . -type phase: , , , , , . type phase: , , , , , , . Pyrite-type phase: , , , .
Phonon dispersion curves of MgO (a) at (b) at . Drawn along .
Free energy of decomposition: . Gray lines show pressures of phase transitions in at each temperature. Pseudopotential LDA results. Thin solid lines separate regions of stability of different phases. All lines are guides to the eye.
Enthalpy of decomposition: . PAW GGA results. PAW potentials had the following parameters: core (radius ) for Mg, core ( radius) for Si core (radius ) for O. The plane wave kinetic energy cutoff of was used, together with Brillouin zone sampling grids similar to those described in Sec. II.
Equations of state of phases in the system: theory and experiment.
Thermodynamic properties (heat capacity and entropy ) of phases in the system: theory and experiment .
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