paper

Electronic structure of TiSe $_{2}$ from a quasi-self-consistent G $_{0}$ W $_{0}$ approach

arXiv:2005.14603 · doi:10.1103/PhysRevB.103.075101

Abstract

In 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 TiSe $_{2}$ , M. Hellgren et al. [Phys. Rev. Lett. 119, 176401 (2017)]. The $G W$ approximation provides a parameter-free description of screened exchange but is usually employed perturbatively ( $G_{0} W_{0}$ ) making results more or less dependent on the starting point. In this work, we develop a quasi-self-consistent extension of $G_{0} W_{0}$ based on the random phase approximation (RPA) and the optimized effective potential of hybrid density functional theory. This approach generates an optimal $G_{0} W_{0}$ 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 TiS $_{2}$ and TiSe $_{2}$ . We find the high-temperature phase of TiSe $_{2}$ to be a semi-metal 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.

11 pages, 5 figures

Electronic structure of TiSe2​ from a quasi-self-consistent G0​W0​ approach

Abstract

Electronic structure of TiSe $_{2}$ from a quasi-self-consistent G $_{0}$ W $_{0}$ approach