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Degeneracy in Density Functional Theory: Topology in v- and n-Space

C. A. Ullrich·W. Kohn
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Abstract

This paper clarifies the topology of the mapping between v- and n-space in fermionic systems. Density manifolds corresponding to degeneracies g=1 and g>1 are shown to have the same mathematical measure: every density near a g-ensemble-v-representable (g-VR) n(r) is also g-VR (except ``boundary densities'' of lower measure). The role of symmetry and the connection between T=0 and T=0+ are discussed. A lattice model and the Be-series are used as illustrations.

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C. A. Ullrich, W. Kohn. 2002-04-24. Degeneracy in Density Functional Theory: Topology in v- and n-Space. https://doi.org/10.1103/physrevlett.89.156401

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