Work

A way to identify whether a DFT gap is from right reasons or error cancellations: The case of copper chalcogenides

Year: 2024

Type: article

Abstract: Gap opening remains elusive in copper chalcogenides (Cu2X, X = S, Se, and Te), not least because Hubbard + U, hybrid functional, and GW methods have also failed. In this work, we elucidate that their failure originates from a severe underestimation of the 4s-3d orbital splitting of the Cu atom, which leads to a band-order inversion in the presence of an anionic crystal field. As a result, the Fermi energy is pinned due to symmetry, yielding an invariant zero gap. Utilizing the hybrid pseudopotentials to correct the underestimation on the atomic side opens up gaps of experimental magnitude in Cu2X, suggesting their predominantly electronic nature. Our work not only clarifies the debate about the Cu2X gap but also provides a way to identify which of the different methods really captures the physical essence and which is the result of error cancellation.

Source: The Journal of Chemical Physics

DOI: 10.1063/5.0196706

Authors: Jiale Shen, Haitao Liu, Yuanchang Li

Institutions: Beijing Institute of Technology, Institute of Applied Physics and Computational Mathematics

Language: English

Topic: Advanced Chemical Physics Studies

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: National Natural Science Foundation of China, Ministry of Science and Technology of the People's Republic of China