[en] 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, nonlocal 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.
Disciplines :
Physics
Author, co-author :
Hellgren, Maria; Université Pierre et Marie Currie - Paris 6 - UPMC > Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie ; University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit
Baima, Jacopo; Université Pierre et Marie Currie - Paris 6 - UPMC > Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie
Bianco, Raffaello; Università di Roma La Sapienza > Dipartimento di Fisica ; Université Pierre et Marie Currie - Paris 6 - UPMC > Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie
Calandra, Matteo; Université Pierre et Marie Currie - Paris 6 - UPMC > Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie
Mauri, Francesco; Fondazione Istituto Italiano di Tecnologia > Graphene Labs ; Università di Roma La Sapienza > Dipartimento di Fisica
Wirtz, Ludger ; University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit
External co-authors :
yes
Language :
English
Title :
Critical Role of the Exchange Interaction for the Electronic Structure and Charge-Density-Wave Formation in TiSe2
Publication date :
24 October 2017
Journal title :
Physical Review Letters
ISSN :
1079-7114
Publisher :
American Physical Society, Ridge, United States - New York