科研之友
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摘要
I study the experimentally observed structural phase transition in NaTiO2 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 (1/2, 1/5, 1/5). These instabilities lead to monoclinic structures without inversion symmetry that are modulated along all three directions. The calculated electronic structures showthat a local bonding instability of the Ti 3d states is associated with the structural transition.
- 出版日期2017-5-22
