| Popis: |
We generalize the DFT/SGGA + U (density functional theory (DFT) at the spin polarized generalized gradient approximation (SGGA) and the Hubbard-U approximation) functional with a view to bring the calculated electronic band structures in agreement with experiment in an efficient way. We show the necessity of incorporating the different components of U, namely the Us/p/d-terms, for the s, p, and d orbitals, to achieve this objective. The proposed generalization requires the knowledge of a few specific spectral features to which we fit the results of the DFT/SGGA + U calculations. In the absence of experimental data we use results obtained by more accurate ab initio calculations such as, the Becke 3-parameter Lee Yang Parr (B3LYP) and the Heyd-Scuseria-Ernzerhof (HSE06) ones for fitting purposes. Application of the method to select materials shows it to be a relatively inexpensive and promising approach for obtaining excitation spectra of materials. |
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