Rationalization of the Hubbard <i>U</i> parameter in CeOx from first principles: Unveiling the role of local structure in screening

Lu, Deyu; Liu, Ping

doi:10.1063/1.4865831

Cited by 40 publications

(34 citation statements)

References 57 publications

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“…More importantly, a further potential deficiency is related to the description of multiple oxidation states present in defective SMO. The formation of oxygen vacancies is generally charge compensated by a reduction of the oxidation state (OS) of some Mn 4+ to Mn 3+ ; transition metals with different OS may not be properly described by the same U [32][33][34][35] .…”

Section: Introductionmentioning

confidence: 99%

Self-consistent site-dependent DFT+ U study of stoichiometric and defective SrMnO3

et al. 2019

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We propose a self-consistent site-dependent Hubbard U approach for DFT+U calculations of defects in complex transition-metal oxides, using Hubbard parameters computed via linear-response theory. The formation of a defect locally perturbs the chemical environment of Hubbard sites in its vicinity, resulting in different Hubbard U parameters for different sites. Using oxygen vacancies in SrMnO3 as a model system, we investigate the dependence of U on the chemical environment and study its influence on the structural, electronic, and magnetic properties of defective bulk and strained thin-film structures. Our results show that a self-consistent U improves the description of stoichiometric bulk SrMnO3 with respect to GGA or GGA+U calculations using an empirical U . For defective systems, U changes as a function of the distance of the Hubbard site from the defect, its oxidation state and the magnetic phase of the bulk structure. Taking into account this dependence, in turn, affects the computed defect formation energies and the predicted strain-and/or defect-induced magnetic phase transitions, especially when occupied localized states appear in the band gap of the material upon defect creation.

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Section: Introductionmentioning

confidence: 99%

Self-consistent site-dependent DFT+ U study of stoichiometric and defective SrMnO3

et al. 2019

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“…In present work, we also derived U d using QE from the Fe3O4 hexagonal cell (shown in Figure 6.3 the B-site does, even if the latter has more bonds with O. This trend is also consistent with other methodology studies on U d dependence [219][220] . (The choice of U p = 5.90 eV has been discussed in our previous work 26 (see details in Chapter 5).)…”

Section: Introductionsupporting

confidence: 88%

Extending accurate density functional modeling for the study of interface reactivity and environmental applications

Xu¹

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To my parents, Fangyan and Xingcheniii ACKNOWLEDGEMENTS Seven years in the University of Iowa have become an amazing chapter in my life.I want to express my gratitude to all the people who have helped and encouraged me during this wonderful journey. And among them all, I would like to thank my advisor, Sara E.Mason, for taking a chance to accept me and opening the entire new world of computational chemistry for me. I could never imagine that I can work on so many challenging projects.Your patience, enthusiasm and trust are not just helping me in my academic progress, but also making me grow up through all the ups and downs. I greatly appreciate your guidance and all of the opportunities to reach out in my graduate career.are not just providing the opportunities for us to apply our computational expertise in solving problems in reality, but also letting us understand the structural and chemical complexity of materials under real conditions that pushed our theoretical models to new levels. Our collaborations have built up current and future directions for our projects, and also provided more prospects in bigger academic communities. I am also thankful for the previous members of the Mason group: Dr. Sai Kumar Ramadugu, Dr. Katie Corum, and Dr. Diane Neff, you were extremely helpful for teaching me the knowledge of quantum theory and computational skills, as well as our collaborations in many different projects. iv I would also like to thank our research specialist: Dr. Joseph W. Bennett, for your in-depth understanding of materials and computational chemistry, and your tireless support for the entire group in every aspect. I am not only making academic progress by learning from your knowledge and experience, but also learning how to become a responsible and competent collaborator in team work, and deal with all the obstacles and setbacks during research. I would further like to thank all the group members, Jennifer, Diamond, Irene, Sidney and Blake, for your support and encouragement. It was a great pleasure to work with all of you. Finally, I want to thank my parents, who were thousands miles away, living on the other side of the Pacific Ocean. I just briefly spent about a month with them during my graduate years, but they provided unconditional love and support to me all the time. You constantly believed in me and encouraged my pursuits. I am eternally grateful. v ABSTRACTDensity functional theory (DFT) has become the most widely used first-principles computational method to simulate different atomic, molecular, and solid phase systems based on the electron density assumptions. The complexity of describing a many-body system has been significantly reduced in DFT. However, it also brings in potential error when dealing with a system that involves the interactions between metallic and nonmetallic species. DFT tends to overly-delocalize the electrons in metallic species and sometimes results in the overestimation of reaction energy, metallic properties in insulators, and predicts relative surface stabilities incorre...

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“…• From the study made by Lu and Liu [26] on cerium compounds presented some characteristics for U values for Ce atoms in different configurations as isolated atoms and ions. They illustrated that the ion charge (Ce atoms, Ce in Ce 3 H x O 7 clusters, or CeO 2 ) does not significantly affect the value of U and that when ions are isolated, the values are much larger (close to 15 for Ce 2.5+ and 18 eV for Ce 3.5+ ).…”

Section: Optimizing the U Valuementioning

confidence: 99%

The DFT+U: Approaches, Accuracy, and Applications

Tolba¹,

Gameel²,

Ali³

et al. 2018

Density Functional Calculations - Recent Progresses of Theory and Application

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This chapter introduces the Hubbard model and its applicability as a corrective tool for accurate modeling of the electronic properties of various classes of systems. The attainment of a correct description of electronic structure is critical for predicting further electronic-related properties, including intermolecular interactions and formation energies. The chapter begins with an introduction to the formulation of density functional theory (DFT) functionals, while addressing the origin of bandgap problem with correlated materials. Then, the corrective approaches proposed to solve the DFT bandgap problem are reviewed, while comparing them in terms of accuracy and computational cost. The Hubbard model will then offer a simple approach to correctly describe the behavior of highly correlated materials, known as the Mott insulators. Based on Hubbard model, DFT+U scheme is built, which is computationally convenient for accurate calculations of electronic structures. Later in this chapter, the computational and semiempirical methods of optimizing the value of the Coulomb interaction potential (U) are discussed, while evaluating the conditions under which it can be most predictive. The chapter focuses on highlighting the use of U to correct the description of the physical properties, by reviewing the results of case studies presented in literature for various classes of materials.

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Rationalization of the Hubbard U parameter in CeOx from first principles: Unveiling the role of local structure in screening

Cited by 40 publications

References 57 publications

Self-consistent site-dependent DFT+ U study of stoichiometric and defective SrMnO3

Self-consistent site-dependent DFT+ U study of stoichiometric and defective SrMnO3

Extending accurate density functional modeling for the study of interface reactivity and environmental applications

The DFT+U: Approaches, Accuracy, and Applications

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