Abstract
Using iron-bearing magnesium silicate perovskite as an example, we show that the Hubbard U correction is not always necessary for calculating the structural and elastic properties of iron-bearing minerals. Instead, it is the choice of DFT functionals (LDA or GGA) that may have greater impact on the quality of the predictive calculation. For iron-bearing minerals, calculations adopting LDA (LDA+U) are generally in better agreement with experimental data than those adopting GGA (GGA+U) after including zero point motion and thermal vibrational effects, as demonstrated by the room-temperature compression curve of (Mg,Fe)SiO3 perovskite. A criterion indicating the necessity of the Hubbard U correction is also discussed. As long as the standard DFT functional produces insulating ground state with correct orbital occupancy, the Hubbard U correction does not affect the computed structural and elastic properties.
Original language | English (US) |
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Pages (from-to) | 13-19 |
Number of pages | 7 |
Journal | Physics of the Earth and Planetary Interiors |
Volume | 185 |
Issue number | 1-2 |
DOIs | |
State | Published - Mar 2011 |
Bibliographical note
Funding Information:This work was supported primarily by the MRSEC Program of the National Science Foundation under Award Number DMR-0212302 and DMR-0819885. It was also supported by NSF grants ATM-0426757 (VLab) and EAR-0815446 . Calculations were performed at the Minnesota Supercomputing Institute (MSI).
Keywords
- First-principles
- GGA+U
- Hubbard U
- Iron-bearing minerals
- LDA+U
- Lower mantle