Exploring weight-dependent density-functional approximations for ensembles in the Hubbard dimer

  title={Exploring weight-dependent density-functional approximations for ensembles in the Hubbard dimer},
  author={Killian Deur and Laurent Mazouin and Bruno Senjean and Emmanuel Fromager},
  journal={The European Physical Journal B},
Abstract Gross–Oliveira–Kohn density-functional theory (GOK-DFT) is an extension of DFT to excited states where the basic variable is the ensemble density, i.e. the weighted sum of ground- and excited-state densities. The ensemble energy (i.e. the weighted sum of ground- and excited-state energies) can be obtained variationally as a functional of the ensemble density. Like in DFT, the key ingredient to model in GOK-DFT is the exchange-correlation functional. Developing density-functional… 
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