Abstract
To explore the origin of the insulating property of layered system ( element) and to find their distorted superstructures, we have investigated the band structures and phonon dispersions of and based on the ab initio density functional theory. We have found three dominant Fermi surface nesting vectors of , and . Phonon softening instabilities occur at the same vectors, which suggests that the lattice instability in Sb layers is driven by the charge density wave instability through the electron-phonon coupling. The linearly superposed mode of two degenerate normal modes at produces the most stable state with a herringbone-type arrangement of Sb dimers. In the ground state, the distorted Sb square sheet shows the insulating behavior in agreement with existing experiments.
- Received 13 January 2015
- Revised 31 March 2015
DOI:https://doi.org/10.1103/PhysRevB.91.165130
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