Ab initio study of phonons and structural stabilities of the perovskite-type MgSiO3

K. Parlinski, Y. Kawazoe

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Using the local-density approximation, calculating the Hellmann-Feynman forces, applying the direct method and deriving the phonon dispersion relations, the stability of the perovskite-like structures of MgSiO3 at T = 0 have been studied. The cubic Pm3̄m phase shows a dispersion-less soft phonon branch spreading from the R to M points of the cubic Brillouin zone. This soft branch persists up to high pressures of 150 GPa. The low-symmetry phases I4/mcm and Imma, P4/mbm can be considered as a result of the soft mode condensation at the M and R points, respectively. These phases prove to be unstable at T = 0. The experimentally observed Pmnb phase is a consequence of the intersection of Imma and P4/mbm space groups. Thus, it can be regarded as a simultaneous condensation of two soft modes: one at the M and a second at the R high-symmetry points of the cubic Brillouin zone. The phonon dispersion relations of Pmnb show that this phase is stable and its optical phonons appear above 4.0 THz only.

Original languageEnglish
Pages (from-to)49-58
Number of pages10
JournalEuropean Physical Journal B
Volume16
Issue number1
DOIs
Publication statusPublished - 2000 Jul 1

Keywords

  • 63.20.-e Phonons in crystal lattices
  • 71.15.Mb Density functional theory, local density approximation
  • 91.35.-x Earth's interior structure and properties

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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