Stefano Falletta^1*, Alfredo Pasquarello^1*

1 Chaire de Simulation à l'Echelle Atomique (CSEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland

* Corresponding authors emails: stefano.falletta@epfl.ch, alfredo.pasquarello@epfl.ch

DOI10.24435/materialscloud:g7-0z [version v1]

Publication date: Jan 06, 2023

How to cite this record

Stefano Falletta, Alfredo Pasquarello, Hubbard U through polaronic defect states, Materials Cloud Archive 2023.4 (2023), doi: 10.24435/materialscloud:g7-0z.

Description

Since the preliminary work of Anisimov and co-workers, the Hubbard corrected DFT+U functional has been used for predicting properties of correlated materials by applying on-site effective Coulomb interactions to specific orbitals. However, the determination of the Hubbard U parameter has remained under intense discussion despite the multitude of approaches proposed. Here, we define a selection criterion based on the use of polaronic defect states for the enforcement of the piecewise linearity of the total energy upon electron occupation. A good agreement with results from piecewise-linear hybrid functionals is found for the electronic and structural properties of polarons, including the formation energies. The values of U determined in this way are found to give a robust description of the polaron energetics upon variation of the considered state. In particular, we also address a polaron hopping pathway, finding that the determined value of U leads to accurate energetics without requiring a configurational-dependent U. It is emphasized that the selection of U should be based on physical properties directly associated with the orbitals to which U is applied, rather than on more global properties such as band gaps and band widths. For comparison, we also determine U through a well-established linear-response scheme finding noticeably different values of U and consequently different formation energies. Possible origins of these discrepancies are discussed. As case studies, we consider the self-trapped electron in BiVO₄, the self-trapped hole in MgO, the Li-trapped hole in MgO, and the Al-trapped hole in 𝛼-SiO₂.

Materials Cloud sections using this data

Files

File name	Size	Description
structures.zip MD5md5:e1e309ddf0677ecdd72016bc8202f810	31.9 KiB	Atomic structures of the materials considered in this work
README.txt MD5md5:8621ca6cfc6a5afb32bdca8422a49b76	998 Bytes	README file

License

Files and data are licensed under the terms of the following license: Creative Commons Attribution 4.0 International.
Metadata, except for email addresses, are licensed under the Creative Commons Attribution Share-Alike 4.0 International license.

External references

Keywords

Polarons density-functional theory DFT+U hybrid functionals self-interaction