charge density waves; excitonic insulator; ab-initio electronic structure
Abstract :
[en] n a previous work, it was shown that the inclusion of exact exchange is essential for a first-principles description of both the electronic and the vibrational properties of TiSe2, M. Hellgren et al. [Phys. Rev. Lett. 119, 176401 (2017)]. The GW approximation provides a parameter-free description of screened exchange but is usually employed perturbatively (G0W0), making results more or less dependent on the starting point. In this work, we develop a quasi-self-consistent extension of G0W0 based on the random phase approximation (RPA) and the optimized effective potential of hybrid density functional theory. This approach generates an optimal G0W0 starting point and a hybrid exchange parameter consistent with the RPA. While self-consistency plays a minor role for systems such as Ar, BN, and ScN, it is shown to be crucial for TiS2 and TiSe2. We find the high-temperature phase of TiSe2 to be a semimetal with a band structure in good agreement with experiment. Furthermore, the optimized hybrid functional agrees well with our previous estimate and therefore accurately reproduces the low-temperature charge-density-wave phase.
Disciplines :
Physics
Author, co-author :
Hellgren, Maria
Baguet, Lucas
Calandra, Matteo
Mauri, Francesco
WIRTZ, Ludger ; University of Luxembourg > Faculty of Science, Technology and Medicine (FSTM) > Department of Physics and Materials Science (DPHYMS)
External co-authors :
yes
Language :
English
Title :
Electronic structure of TiSe2 from a quasi-self-consistent G0W0 approach
Publication date :
2021
Journal title :
Physical Review. B
ISSN :
2469-9950
eISSN :
2469-9969
Publisher :
American Physical Society
Volume :
103
Pages :
075101
Peer reviewed :
Peer Reviewed verified by ORBi
Focus Area :
Physics and Materials Science Computational Sciences
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