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arXiv · 2212.11500

Assignment of excitonic insulators in \textit{ab initio} theories: the case of NiBr$_2$

Stefano Di Sabatino·Alejandro Molina-Sánchez·Pina Romaniello·Davide Sangalli
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Abstract

In this work we perform a detailed first-principles analysis of the electronic and optical properties of NiBr$_2$ within the state-of-the-art $GW$+BSE scheme to determine whether this system displays negative excitonic energies, which would identify it as an (half) excitonic insulator. Particular attention is payed to the convergence of the $GW$ band structure and to the consistency between approximations employed in the ground-state calculations and approximations employed in the linear response calculations. We show that these two issues play a crucial role in identifying the excitonic nature of NiBr$_2$.

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Stefano Di Sabatino, Alejandro Molina-Sánchez, Pina Romaniello, Davide Sangalli. 2022-12-22. Assignment of excitonic insulators in \textit{ab initio} theories: the case of NiBr$_2$. https://doi.org/10.1103/physrevb.107.115121

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