Diffusion quantum Monte Carlo calculations of SrFeO3 and LaFeO3

Santana, Juan A.; Krogel, Jaron T.; Kent, Paul; Reboredo, Fernando A.

doi:10.1063/1.4994083

Cited by 32 publications

(53 citation statements)

References 95 publications

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“…In general, the perovskites exhibit an increased reducibility as we move from LaScO 3 to LaCuO 3 . However, the oxygen vacancy formation energy in LaFeO 3 is exceptionally high (4.7 -4.9 eV), regardless of the crystal structures adopted and the exchange-correlation functionals used (By using the quantum Monte Carlo method, Santana et al 74 even obtained a high value of 6.24 eV for LaFeO 3 ). This finding has been verified by previous experimental observations that the Fe-O bond in LaFeO 3 is even harder to break than the Mn-O bond in LaMnO 3 [68][69] .…”

Section: Contributions To Oxygen Vacancy Formation Energymentioning

confidence: 99%

Electronic Origin of Oxygen Transport Behavior in La-Based Perovskites: A Density Functional Theory Study

Zheng

Zhang

et al. 2018

J. Phys. Chem. C

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Understanding the oxygen transport behavior in perovskites is of central importance for tailoring their physical and chemical properties to various practical applications. In this contribution, periodic DFT+U calculations have been performed to unravel the electronic origin of the oxygen mobility difference in La-based perovskites involving 3d-block transition metals from Sc through Cu. Calculated results indicate that the perovskites generally exhibit an increased reducibility on going from LaScO 3 to LaCuO 3 , and the exceptionally high oxygen vacancy formation energy in LaFeO 3 is due to the significant lowering of the electron exchange stabilization upon reduction. The oxygen migration barrier in the first four perovskites varies from 1.2 eV to 2.1 eV while that for the later five materials is much lower and lies between 0.4 and 0.9 eV. Electronic structure analysis indicates this abrupt change in the migration barrier can be attributed to the different degrees of charge redistribution on the central transition-metal ion during the migration process. Linear scaling relations are established to show that the oxygen bulk diffusion coefficient is governed essentially by the oxygen concentration rather than by the migration barrier. The actual partial charge on the transition metal or oxygen ion explains the electronic origin of the different oxygen transport properties of La-based perovskites, and the observed trend can be described by using the oxygen vacancy formation energy as a good descriptor.

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Section: Contributions To Oxygen Vacancy Formation Energymentioning

confidence: 99%

Electronic Origin of Oxygen Transport Behavior in La-Based Perovskites: A Density Functional Theory Study

Zheng

Zhang

et al. 2018

J. Phys. Chem. C

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“…The optimized pseudopotentials presented here have also been employed in a few recent studies of bulk transition metal oxides [65][66][67] as well as bulk metals 65,68 . For comparison with our dimer results, we reproduce the bulk data in Table IV with permission of the authors.…”

Section: Comparison With Bulk Studiesmentioning

confidence: 99%

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

2016

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Quantum Monte Carlo (QMC) calculations of transition metal oxides are partially limited by the availability of high quality pseudopotentials that are both accurate in QMC and compatible with major planewave electronic structure codes. We have generated a set of neon core pseudopotentials with small cutoff radii for the early transition metal elements Sc to Zn within the local density approximation of density functional theory. The pseudopotentials have been directly tested for accuracy within QMC by calculating the first through fourth ionization potentials of the isolated transition metal (M) atoms and the binding curve of each M-O dimer. We find the ionization potentials to be accurate to 0.16(1) eV, on average, relative to experiment. The equilibrium bond lengths of the dimers are within 0.5(1)% of experimental values, on average, and the binding energies are also typically accurate to 0.18(3) eV. The level of accuracy we find for atoms and dimers is comparable to what has recently been observed for bulk metals and oxides using the same pseudpotentials. Our QMC pseudopotential results also compare well with the findings of previous QMC studies and benchmark quantum chemical calculations.PACS numbers: 71.15.Dx, 71.15.Nc Transition metal oxides are an essential class of materials for energy applications. These materials find applications as diverse as catalysis, energy storage, and superconductivity. The ability to tailor the electronic functionality of transition metal oxides is clearly bolstered by continuing to develop a detailed theoretical understanding of these materials. Unfortunately it is this same class of materials that presents some of the greatest resistance to detailed theoretical characterization. Part of this challenge directly relates to the more localized electrons occupying the partially filled d states of the transition metal cations, leading to strong electron-electron interactions. Early characterizations of transition metal oxides by band theory incorrectly predicted many of them to be metals 1 . This departure from the expectations of band theory has lead to the widespread acceptance of strong electron correlation in these materials, in essence meaning that the Coulomb repulsion among electrons needs to be taken into account with some care. Continuum quantum Monte Carlo (QMC) methods 2 have the potential to address this need, as they are capable of taking the many body correlations of interacting electrons explicitly into account with few fundamental approximations. Though the application of such methods generally comes at a high computational cost, with the dramatic increase in available computing power seen in recent years these methods are now being brought to bear 3-9 on this challenging class of materials.One of the most prominent approximations involved in the practical application of quantum Monte Carlo techniques is the use of pseudopotentials to remove the high-energy core electrons. The fundamental idea behind pseudopotentials is that they preserve the electronic characteri...

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“…DMC previously predicted the correct energetic ordering between the three polymorphs of CoO, surpassing the accuracy of DFT approximations [46]. DMC was shown to yield accurate energies for Lacontaining compounds as well [47,48]. Thanks to its favorable computational scaling, O(N 3 ), DMC can be an ideal theoretical method to study LCO.…”

Section: Introductionmentioning

confidence: 99%

Structural, electronic, and magnetic properties of bulk and epitaxial LaCoO3 through diffusion Monte Carlo

Saritas

Krogel

Okamoto

et al. 2019

Phys. Rev. Materials

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Magnetism in lanthanum cobaltite (LCO, LaCoO3) appears to be strongly dependent on strain, defects, and nanostructuring. LCO on strontium titanate (STO, SrTiO3) is a ferromagnet with an interesting strain relaxation mechanism that yields a lattice modulation. However, the driving force of the ferromagnetism is still controversial. Experiments debate between a vacancy-driven or straindriven mechanism for epitaxial LCO's ferromagnetism. We found that a weak lateral modulation of the superstructure is sufficient to promote ferromagnetism. Our research also showed that ferromagnetism appears under uniaxial compression and expansion. Although earlier experiments suggest that bulk LCO is nonmagnetic, our Diffusion Monte Carlo calculations found that magnetic phases have a lower energy ground state for bulk LCO. This article discusses recent experiments indicating a more complicated picture for the bulk magnetism and closer agreement with our calculations. The role of defects are also discussed through excited-state calculations. arXiv:1908.02811v3 [cond-mat.mtrl-sci]

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Diffusion quantum Monte Carlo calculations of SrFeO3 and LaFeO3

Cited by 32 publications

References 95 publications

Electronic Origin of Oxygen Transport Behavior in La-Based Perovskites: A Density Functional Theory Study

Electronic Origin of Oxygen Transport Behavior in La-Based Perovskites: A Density Functional Theory Study

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

Structural, electronic, and magnetic properties of bulk and epitaxial LaCoO3 through diffusion Monte Carlo

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