Computational treatment of lanthanide dopants in oxides by DFT with Hubbard corrections Dan Criveanu, Katherine Inzani School of Chemistry, University of Nottingham, UK Density functional theory (DFT) is a computationally efficient choice for computing the quantum chemical properties of material systems. However, electron over-delocalization presents a problem in the DFT treatment of lanthanide elements as d - and f -electrons are highly localised. 1 One way to address this is with additive corrections to the DFT energy such as DFT+U 2-4 , in which a Hubbard U parameter is introduced to enforce localisation of a given subshell. This method has been highly successful for transition metals, and recent developments have also shown its applicability in the treatment of lanthanide compounds. 5,6 Here, we investigate the use of these methods for lanthanide dopants in wide band gap oxides. Using cerium-doped yttrium aluminium garnet (YAG:Ce) as a model system, we compare the effect of DFT+U corrections on the electronic structure, and we show the limitations of self-consistent determination of U. 7 Furthermore, we explore methods that address metastability issues introduced by DFT+U, 8-10 which are particularly problematic for f -electron systems. 10 We identify occupation matrix control 8 as the preferred method to address metastability issues in YAG:Ce due to its ability to find the lowest energy electronic state compared to U-ramping. 9 Successful implementation of such low-computational cost corrections would enable further theory-led innovations in lanthanide-doped oxides, with wide-ranging implications from lighting to quantum technologies. References 1. K. Capelle and V. L. Campo, Phys. Rep., 2013, 528, 91–159. 2. V. I. Anisimov et al., Phys. Rev. B, 1991, 44, 943–954. 3. A. I. Liechtenstein et al., Phys. Rev. B, 1995, 52, R5467–R5470. 4. S. L. Dudarev et al., Phys. Rev. B, 1998, 57, 1505–1509. 5. A. Canning et al.,Phys. Rev. B, 2011,83, 125115.
6. A. Blanca Romero et al.,J. Comput. Chem., 2014,35, 1339–1346. 7. M. Cococcioni and S. de Gironcoli, Phys. Rev. B, 2005, 71, 035105. 8. B. Dorado et al., Phys. Rev. B, 2010, 82, 035114. 9. B. Meredig et al., Phys. Rev. B, 2010, 82, 195128. 10. J. P. Allen and G. W. Watson,Phys. Chem. Chem.Phys., 2014,16, 21016–21031.
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