Abstract
I study the experimentally observed structural phase transition in using density functional calculations. I do not find the previously proposed low-temperature structure energetically favorable with respect to the high-temperature rhombohedral structure. The calculated phonon dispersions of the rhombohedral phase show dynamical instabilities at several inequivalent parts of the Brillouin zone, including at the wave vector . These instabilities lead to monoclinic structures without inversion symmetry that are modulated along all three directions. The calculated electronic structures show that a local bonding instability of the Ti states is associated with the structural transition.
- Received 14 January 2017
DOI:https://doi.org/10.1103/PhysRevB.95.195149
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