Description of light-element magnetic systems via density functional theory plus U with an example system of fluorinated boron nitride: An efficient alternative to hybrid functional approach

[Display omitted] •GGA and HSE both are defective for light-element magnets.•Appling U to the N-2p orbitals can reproduce the HSE result well.•Using the GGA+U for large light-element magnetic systems is proposed. It is well known that for light-element magnetic materials density functional theory (D...

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Bibliographic Details
Published in:Computational materials science 2018-04, Vol.146, p.84-89
Main Authors: Li, Wanxue, Xin, Xiaojun, Wang, Hongyan, Guo, Chunsheng, Jiang, Hong, Zhao, Yong
Format: Article
Language:English
Subjects:
DFT+U
Hybrid functionals
Light-element magnets
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Summary:[Display omitted] •GGA and HSE both are defective for light-element magnets.•Appling U to the N-2p orbitals can reproduce the HSE result well.•Using the GGA+U for large light-element magnetic systems is proposed. It is well known that for light-element magnetic materials density functional theory (DFT) in the local density approximation or generalized gradient approximation (LDA or GGA) underestimates the electron localization effects and tends to give misleading results. Hybrid functionals such as Heyd-Scuseria-Ernzerhof (HSE) perform much better while being computationally expensive, especially for extended systems. In order to go beyond semi-local DFT without needing to calculate the expensive Fock exchange, here we explore the performance of the more efficient GGA plus the Hubbard U correction (GGA+U) approach to light-element magnetic materials by considering fluorinated boron nitride (F-BN) sheets and nanotubes as model systems. By applying the Hubbard U correction to the N-2p orbitals with the value of U determined by fitting the HSE results in a particular F-BN sheet, it is found that the GGA+U approach shows a great improvement to GGA in describing the magnetic properties of F-BN systems with an accuracy close to that of the HSE hybrid functional approach. It indicates the possibility of using the ad hoc correction approach as an efficient alternative to study light-element magnetic materials, especially for large systems where calculations based on hybrid functionals become cost-demanding.
ISSN:0927-0256
1879-0801
DOI:10.1016/j.commatsci.2018.01.003