Spin density stabilization of local distortions induced by a monovacancy in $\delta$ -Pu

Journal Article · 21 August 2018 · Physical Review Materials

DOI: https://doi.org/10.1103/PhysRevMaterials.2.085005 · OSTI ID:1483534

Hernandez, Sarah C. ^[1]; Freibert, Franz J. ^[1]; Hoagland, Richard G. ^[1]; Uberuaga, Blas P. ^[1]; Wills, John M. ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Density functional theory calculations elucidate crystallographic and electronic structural responses of the fcc delta phase of plutonium (δ-Pu) to point defects. Discussed are responses that vary from a defect exhibiting a local structural instability common in fcc metals to an unusual defect structure that mimics properties similar to the monoclinic α phase. In the prior case, the existence of a self-vacancy when ionic relaxation is allowed induces in the fcc lattice a local tetragonal instability in nearest-neighbor atoms, slight electronic charge increase, and a spin-density decrease. However, in the latter case, after ionic relaxation, the defect is not recognizable as the structure of a vacant site common to many simple fcc metals, but is a complex extended defect involving neighboring atoms to collectively exhibit loss of lattice symmetry through formation of short Pu-Pu bonds and associated narrow bands at the Fermi energy. Partial density of states (PDOS) indicates that these narrow bands form as spectral weighting from the less energetic 6d electronic states is shifted to the 5f electronic states by means of the spin density, which occupies states at the Fermi energy. Finally, the PDOS of a 5f system exhibiting narrow bands at the Fermi energy is associated with the formation of an unusual defect structure in the lattice.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE; LANL Laboratory Directed Research and Development (LDRD) Program
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 1483534
• Alternate ID(s): OSTI ID: 1465607
• Report Number(s): LA-UR-18-23844
• Journal Information: Physical Review Materials, Vol. 2, Issue 8; ISSN 2475-9953
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English