Nature of the electronic band gap in lanthanide oxides

Abstract

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Accurate electronic structures of the technologically important lanthanide/rare-earth sesquioxides (Ln 2 O 3 , with Ln = La, . . . ,Lu) and CeO 2 have been calculated using hybrid density functionals HSE03, HSE06, and screened exchange (sX-LDA). We find that these density functional methods describe the strongly correlated Ln f electrons as well as the recent G 0 W 0 @LDA+U results, generally yielding the correct band gaps and trends across the Ln period. For HSE, the band gap between O 2p states and lanthanide 5d states is nearly independent of the lanthanide, while the minimum gap varies as filled or empty Ln 4f states come into this gap. sX-LDA predicts the unoccupied 4f levels at higher energies, which leads to a better agreement with experiments for Sm

Accurate screened exchange band structures for the transition metal monoxides MnO, FeO, CoO and NiO

“…Most notably, Rödl et al 20 showed that the screened hy-brid functional HSE03, which they used as input for their G 0 W 0 calculations, yields good band gaps on its own. We recently reported that the screened hybrid functional 'screened-exchange LDA' (sX-LDA) successfully reproduces the electronic properties of CeO 2 , as well as those of lanthanide (X=La,Ce,...,Lu) 29 and transition metal (X=Ti, Cr, Fe) 38 sesquioxides X 2 O 3 . Interestingly, we observed that variations in treatment of the screened exchange interaction in the hybrid functional approach can lead to qualitative differences of the predicted properties.…”

“…Hybrid functionals have been shown to be versatile methods for the study of correlated materials, often on par with quasiparticle methods [27][28][29] , while generally performing great for sp semiconductors and materials of practical interest, such as GaN or ZnO 27 . A number of hybrid functional studies on late transition metal oxides has been reported 17,20,[30][31][32][33][34][35][36][37][38] , with band gaps varying with the fraction of included Hartree-Fock exchange.…”

A Macrocyclic Chelator That Selectively Binds Ln4+ over Ln3+ by a Factor of 1029

“…15,18,[31][32][33][34][35][36] Extended solids including CeO2 have also served as important test cases for evaluating whether accurate theoretical methodology can treat the 4f-electrons simply as part of the core, or whether a more demanding approach should be followed that allows the 4f-electrons to delocalize and participate in bonding. [37][38][39][40][41][42][43][44][45][46] Cerium intermetallics have been at the forefront of condensed matter physics and development of the Anderson impurity model for heavy fermion systems and Kondo insulators. 47 For example, Ce L3-and M5,4-edge XANES spectroscopic investigations of CeRu3, CeRh3, and CePt3 have provided evidence for 4f-electron delocalization, 20,23,[48][49] and L3-edge investigations of intermetallics such as CeCoIn5 have led to new understanding of their remarkable magnetic and superconducting properties.…”

Calculation of metallic and insulating phases of V2O3 by hybrid density functionals

“…Hybrid functionals have been used to calculate the single particle band structures of various transition metal oxides. [50][51][52][53][54] The HSE functional was used previously to study the MIT in VO 2 with changing the crystal structure, 50 but based on experimental atomic coordinates. Here, we find that the sX functional will reproduce the correct single-particle electronic structure in all the three phases of V 2 O 3 without any fitting parameter.…”