False-positive and False-negative assignments of Topological Insulators in Density-Functional Theory and Hybrids

TL;DR

This paper examines the limitations of Density-Functional Theory in accurately identifying topological insulators, highlighting false positives caused by methodological and structural inaccuracies, and emphasizes the need for more precise approaches.

Contribution

It demonstrates that DFT can produce false-positive topological insulator predictions and underscores the importance of using accurate crystal structures and Hamiltonians for reliable identification.

Findings

DFT can misidentify non-topological materials as TIs.

Incorrect crystal structure choices lead to false-positive TI predictions.

Using GW approach reduces false positives in topological classification.

Abstract

Density-functional Theory (DFT) approaches have recently been used to judge the topological order of various materials despite its well-known band gap underestimation. Use of the more accurate quasi-particle GW approach reveals here few cases where DFT identifications are false-positive, possibly misguiding experimental searches of materials that are topological insulators (TI) in DFT but not expected to be TI in reality. We also present the case of false-positive due to the incorrect choice of crystal structures and adress the relevancy of such choice of crystal structure with respect to the ground state one and thermodynamical instability with respect to binary competing phases. We conclude that it is then necessary to consider both the correct ground state crystal structure and the correct Hamiltonian in order to predict new TI.