First-principles calculations of hematite (α-Fe2O3) by self-consistent DFT+U+V

Nelson Naveas; Ruth Pulido; Carlo Marini; Jacobo Hernández-Montelongo; Miguel Manso Silván

doi:10.1016/j.isci.2023.106033

First-principles calculations of hematite (α-Fe₂O₃) by self-consistent DFT+U+V

iScience. 2023 Jan 24;26(2):106033. doi: 10.1016/j.isci.2023.106033. eCollection 2023 Feb 17.

Authors

Nelson Naveas^{1

2

3}, Ruth Pulido^{1

2

3}, Carlo Marini⁴, Jacobo Hernández-Montelongo⁵, Miguel Manso Silván^{1

3

6}

Affiliations

¹ Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
² Departamento de Ingeniería Química y Procesos de Minerales, Universidad de Antofagasta, Avenida Angamos 601, Antofagasta, Chile.
³ Instituto Universitario de Ciencia de Materiales "Nicolás Cabrera" (INC), Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049 Madrid, Spain.
⁴ CELLS-ALBA Synchrotron, 08290 Cerdanyola del Valles, Spain.
⁵ Departamento de Ciencias Matemáticas y Físicas, UC Temuco, 4813302 Temuco, Chile.
⁶ Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049 Madrid, Spain.

Abstract

Owing to the confined Fe-3d orbitals and self-interaction error of exchange-correlation functionals, approximate DFT fails to describe iron oxides electronic structure and magnetic properties accurately. Hybrid DFT or DFT + U can solve these problems, but the former is expensive, and the latter only considers on-site interactions. Here, we used DFT + U + V, a DFT + U extension including inter-site interactions, to simulate the structural, magnetic, and electronic properties, along with Fe and O K-edge XAS spectra of α-Fe₂O₃. Two types of atomic orbital projectors were studied, orthogonalized and non-orthogonalized. DFT + U + V improves the description of the structural, magnetic, and electronic properties of α-Fe₂O₃ compared to approximate DFT. The accuracy of the correction depends on the orbital projector used. DFT + U + V with orthogonalized projectors achieves the best experimental agreement at a fraction of hybrid DFT cost. This work emphasizes the importance of inter-site interactions and the type of atomic orbital projectors used in the theoretical research of α-Fe₂O₃.

Keywords: Computational physics; Condensed matter properties; Magnetism.