Critical Role of the Exchange Interaction for the Electronic Structure and Charge-Density-Wave Formation in TiSe 2

Abstract : We show that the inclusion of screened exchange via hybrid functionals provides a unified description of the electronic and vibrational properties of TiSe2. In contrast to local approximations in density functional theory, the explicit inclusion of exact, non-local exchange captures the effects of the electron-electron interaction needed to both separate the Ti-d states from the Se-p states and stabilize the charge-density-wave (CDW) (or low-T) phase via the formation of a p − d hybridized state. We further show that this leads to an enhanced electron-phonon coupling that can drive the transition even if a small gap opens in the high-T phase. Finally, we demonstrate that the hybrid functionals can generate a CDW phase where the electronic bands, the geometry, and the phonon frequencies are in agreement with experiments.
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Contributor : Maria Hellgren <>
Submitted on : Tuesday, November 27, 2018 - 6:09:03 PM
Last modification on : Tuesday, May 14, 2019 - 10:43:09 AM

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Maria Hellgren, Jacopo Baima, Raffaello Bianco, Matteo Calandra, Francesco Mauri, et al.. Critical Role of the Exchange Interaction for the Electronic Structure and Charge-Density-Wave Formation in TiSe 2. Physical Review Letters, American Physical Society, 2017, 119 (17), pp.176401. ⟨10.1103/PhysRevLett.119.176401⟩. ⟨hal-01936978⟩

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