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arXiv · 1704.05669

Critical role of the exchange interaction for the electronic structure and charge-density-wave formation in TiSe2

Maria Hellgren·Jacopo Baima·Raffaello Bianco·Matteo Calandra·Francesco Mauri·Ludger Wirtz
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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 through 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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Maria Hellgren, Jacopo Baima, Raffaello Bianco, Matteo Calandra, Francesco Mauri, Ludger Wirtz. 2017-10-18. Critical role of the exchange interaction for the electronic structure and charge-density-wave formation in TiSe2. https://doi.org/10.1103/physrevlett.119.176401

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