The magic of plutonium: 5f electrons and phase instability

Hecker, Siegfried S.

doi:10.1007/s11661-006-0200-1

Cited by 57 publications

(61 citation statements)

References 52 publications

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“…As mentioned above, our test case for correlation is elemental Pu, an actinide metal, which exhibits large volume changes compared to predictions from band structure theory that are clearly due to correlation effects [47][48][49][50][51] . The large variation in volumes is controlled by the amount of strong f -bonding, which is due to direct f -f wave-function overlap.…”

Section: Theoretical Methodsmentioning

confidence: 99%

Electronic correlation strength of Pu

et al. 2013

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A new electronic quantity, the correlation strength, is defined as a necessary step for understanding the properties and trends in strongly correlated electronic materials. As a test case, this is applied to the different phases of elemental Pu. Within the GW approximation we have surprisingly found a "universal" scaling relationship, where the f-electron bandwidth reduction due to correlation effects is shown to depend only upon the local density approximation (LDA) bandwidth and is otherwise independent of crystal structure and lattice constant.

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Section: Theoretical Methodsmentioning

confidence: 99%

Electronic correlation strength of Pu

et al. 2013

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“…Within ~200 nanoseconds most of the Frenkel pairs annihilate, leaving a small amount of damage in the lattice. Over time, this damage accumulates in the form of defects, such as vacancies, interstitials, dislocations, and He bubbles (Hecker, 2004;Schwartz et al, 2005). What this means is that not only are actinide metals intrinsically complicated, but lattice damage accumulates over time due to self irradiation, further complicating the physics of the materials.…”

Section: B Actinide Series Overviewmentioning

confidence: 99%

Nature of the5fstates in actinide metals

2009

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Actinide elements produce a plethora of interesting physical behaviors due to the 5f states. This review compiles and analyzes progress in understanding of the electronic and magnetic structure of the 5f states in actinide metals. Particular interest is given to electron energy-loss spectroscopy and many-electron atomic spectral calculations, since there is now an appreciable library of core d → valence f transitions for Th, U, Np, Pu, Am, and Cm. These results are interwoven and discussed against published experimental data, such as x-ray photoemission and absorption spectroscopy, transport measurements, and electron, x-ray, and neutron diffraction, as well as theoretical results, such as density-functional theory and dynamical mean-field theory.

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“…It has long been recognized that 5f electron-electron correlations play an important role in the light actinides [1,2], becoming increasingly significant as one moves across this series and the atomic number Z increases. This culminates in Pu, which has many extreme physical properties that are driven by these correlations [3], such as the large volume expansion for the α to δ phase transformation [4,5]. What is less clear is the role of correlations for Z's less than Pu.…”

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confidence: 99%

“…This culminates in Pu, which has many extreme physical properties that are driven by these correlations [3], such as the large volume expansion for the α to δ phase transformation [4,5]. What is less clear is the role of correlations for Z's less than Pu.…”

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confidence: 99%

Many-body electronic structure of metallicα-uranium

et al. 2008

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We present results for the electronic structure of α uranium using a recently developed quasiparticle self-consistent GW method (QSGW ). This is the first time that the f -orbital electron-electron interactions in an actinide has been treated by a first-principles method beyond the level of the generalized gradient approximation (GGA) to the local density approximation (LDA). We show that the QSGW approximation predicts an f -level shift upwards of about 0.5 eV with respect to the other metallic s-d states and that there is a significant f -band narrowing when compared to LDA band-structure results. Nonetheless, because of the overall low f -electron occupation number in uranium, ground-state properties and the occupied band structure around the Fermi energy is not significantly affected. The correlations predominate in the unoccupied part of the f states. This provides the first formal justification for the success of LDA and GGA calculations in describing the ground-state properties of this material. It has long been recognized that 5f electron-electron correlations play an important role in the light actinides [1,2], becoming increasingly significant as one moves across this series and the atomic number Z increases. This culminates in Pu, which has many extreme physical properties that are driven by these correlations [3], such as the large volume expansion for the α to δ phase transformation [4,5]. What is less clear is the role of correlations for Z's less than Pu. Uranium stands at a kind of threshold in this regard. Experimentally, the pure material is weak to moderately correlated [6], since specific heat enhancements are moderate and no convincing satellite or Kondo photoemission peaks are observed, which is consistent with the success of band-structure in predicting materials properties [7,8]. At the same time, when the uranium atoms are pushed apart by other elements, they form many heavy fermion and other strongly correlated uranium compounds [9]. In this regard, uranium is an inviting target to study, since it should have interesting correlation effects beyond conventional metals like copper or aluminum, and yet these should be weak enough to have some hope of accurately calculating them. It is thus an important testing ground for correlation theory and how many-body effects correct conventional LDA band structures.The most widely used electronic-structure method, the local density approximation (LDA), has been an immensely successful tool that reasonably predicts groundstate properties of weakly correlated systems. The LDA is much less successful at predicting optical properties of such systems, and its failures become more serious as correlations become stronger. Recent photoemission spectroscopy on high quality uranium singe crystals has revealed additional information about the electronic structure of this material [10,11]. Comparison with LDA calculated electronic bands shows some disagreement between experiment and theory. Because of the poor treatment of electron correlations by LDA it is dif...

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The magic of plutonium: 5f electrons and phase instability

Cited by 57 publications

References 52 publications

Electronic correlation strength of Pu

Electronic correlation strength of Pu

Nature of the5fstates in actinide metals

Many-body electronic structure of metallicα-uranium

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