First-principles calculations of the ferroelastic transition between rutile-type and CaCl2 -type SiO2 at high pressures
Abstract
The tetragonal to orthorhombic ferroelastic phase transition between rutile- and CaCl2 -type SiO2 at high pressures is studied using first-principles calculations and the Landau free-energy expansion. The phase transition is systematically investigated in terms of characteristic phonon modes with B1g and Ag symmetries, shear moduli, transverse-acoustic mode, rotation angle of the SiO6 octahedra, spontaneous symmetry-breaking and volume strains, and enthalpy. The results show that these physical behaviors at the transition are well described using the Landau free-energy expansion parametrized by the first-principles calculations.
- Publication:
-
Physical Review B
- Pub Date:
- October 2008
- DOI:
- 10.1103/PhysRevB.78.134106
- Bibcode:
- 2008PhRvB..78m4106T
- Keywords:
-
- 62.50.-p;
- 62.20.de;
- 63.20.-e;
- 61.50.Ks;
- High-pressure effects in solids and liquids;
- Elastic moduli;
- Phonons in crystal lattices;
- Crystallographic aspects of phase transformations;
- pressure effects