Understanding STM images and EELS spectra of oxides with strongly correlated electrons: a comparison of nickel and uranium oxides

Dudarev, S. L.; Castell, Martin R.; Botton, Gianluigi A.; Savrasov, S. Y.; Muggelberg, C.; Briggs, G. Andrew D.; Sutton, A. P.; Goddard, D. T.

doi:10.1016/s0968-4328(99)00115-8

Cited by 98 publications

(78 citation statements)

References 34 publications

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“…The U-J value of 6 eV used in this study produces good agreement with the experimental EELS spectrum as demonstrated in Figure 1c. Dudarev et al used a slightly smaller value of U-J = 4 eV [6]; it appears that either value predicts correct spectroscopic character associated with the oxygen K-edge for urania.…”

Section: Discussionmentioning

confidence: 99%

Electronic structure of oxide fuels from experiment and first principles calculations

Aguiar

Grønbech‐Jensen

Perlov³

et al. 2010

J. Phys.: Conf. Ser.

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Abstract. Energy loss spectra from a variety of cubic oxides are compared with ab-initio calculations based on the density functional plane wave method (CASTEP). In order to obtain agreement between experimental and theoretical spectra, unique material specific considerations were taken into account. The spectra were calculated using various approximations to describe core-hole effects and electron correlation. The calculations are based on both the generalized gradient approach and the local spin density approximation when dealing with the correlation in to show qualitative agreement with the sensitive oxygen K-edge spectra in ceria, zirconia, and urania. Comparison of experimental and theoretical results let us characterize the main electronic interactions responsible for both the electronic structure and the resulting EELS spectra of the compounds in question.

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Section: Discussionmentioning

confidence: 99%

Electronic structure of oxide fuels from experiment and first principles calculations

Aguiar

Grønbech‐Jensen

Perlov³

et al. 2010

J. Phys.: Conf. Ser.

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“…The plutonium 6s 2 7s 2 6p 6 6d 2 5f 4 , and the oxygen 2s 2 2p 4 electrons are treated as valence electrons. The exchange and correlation effects are treated in both the LDA and the GGA [31], based on which the strong on-site Coulomb repulsion among the localized Pu 5f electrons is described by using the LDA/GGA+U formalisms formulated by Dudarev et al [13][14][15]. As concluded in some previous DFT studies [19,20,22,24], although the pure LDA and GGA fail to depict the electronic structure, especially the insulating nature and the occupied-state character of bulk AFM PuO 2 , the LDA/GGA+U approaches can capture the Mott insulating properties of the strongly correlated Pu 5f electrons adequately and well reproduce experimental ground-state parameters by tuning the effective Hubbard parameter U eff at ∼4 eV.…”

Section: A Dft Calculationsmentioning

confidence: 99%

First-principles study of surface properties of PuO2: Effects of thickness and O-vacancy on surface stability and chemical activity

Sun

Liu

Song

et al. 2012

Journal of Nuclear Materials

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The (111), (110), and (001) surfaces properties of PuO 2 are studied by using density-functional theory+U method. The total-energy static calculations determine the relative order of stability for low-index PuO 2 surfaces, namely, O-terminated (111) > (110) > defective (001) > polar (001).The effect of thickness is shown to modestly modulate the surface stability and chemical activity of the (110) (111) is found to be the most stable surface. Whereas under O-reducing conditions, the on-surface O-vacancy of C V = 1/9 is stable, and for high reducing conditions, the (111) surface with nearly one monolayer subsurface oxygen removed (C V = 8/9) becomes most stable.

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“…Due to its critical importance in the nuclear fuel cycle and to the complex electronic structure arising from a partially occupied 5f orbital, uranium dioxide (UO 2 ) has been studied extensively in experiments [1][2][3][4][5][6] and computational simulations [7][8][9][10][11][12][13][14][15]. The 5f electrons in UO 2 play a pivotal role in understanding its electronic, thermodynamic, and magnetic properties [16].…”

Section: Introductionmentioning

confidence: 99%

Phonon spectrum, thermodynamic properties, and pressure-temperature phase diagram of uranium dioxide

et al. 2013

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We present a study of the structural phase transition and the mechanical and thermodynamic properties of UO2 by means of the local density approximation (LDA)+U approach. A phase transition pressure of 40 GPa is obtained from theory at 0 K, and agrees well with the experimental value of 42 GPa. The pressure-induced enhancements of elastic constants, elastic moduli, elastic wave velocities, and Debye temperature of the ground-state fluorite phase are predicted. The phonon spectra of both the ground state fluorite structure and high pressure cotunnite structure calculated by the supercell approach show that the cotunnite structure is dynamically unstable under ambient pressure. Based on the imaginary mode along the Γ−X direction and soft phonon mode along the Γ−Z direction, a transition path from cotunnite to fluorite has been identified. We calculate the lattice vibrational energy in the quasiharmonic approximation using both first-principles phonon density of state and the Debye model. The calculated temperature dependence of lattice parameter, entropy, and specific heat agrees well with experimental observations in the low temperature domain. The difference of the Gibbs free energy between the two phases of UO2 has predicted a boundary in the pressure-temperature phase diagram. The solid-liquid boundary is approximated by an empirical equation using our calculated elastic constants.

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Understanding STM images and EELS spectra of oxides with strongly correlated electrons: a comparison of nickel and uranium oxides

Cited by 98 publications

References 34 publications

Electronic structure of oxide fuels from experiment and first principles calculations

Electronic structure of oxide fuels from experiment and first principles calculations

First-principles study of surface properties of PuO2: Effects of thickness and O-vacancy on surface stability and chemical activity

Phonon spectrum, thermodynamic properties, and pressure-temperature phase diagram of uranium dioxide

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