Ab initio derivation of low-energy model for κ-ET type organic conductors

Kazuma Nakamura*, Yoshihide Yoshimoto, Taichi Kosugi, Ryotaro Arita, Masatoshi Imada

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

135 Citations (Scopus)


We derive effective Hubbard-type Hamiltonians of κ-(BEDT-TTF) 2X, using an ab initio downfolding technique, for the first time for organic conductors. They contain dispersions of the highest occupied Wannier-type molecular orbitals with the nearest neighbor transfer t ∼ 0:067 eV for a metal X - Cu(NCS) 2 and 0.055 eV for a Mott insulator X - Cu 2(CN) 3, as well as screened Coulomb interactions. It shows unexpected differences from the conventional extended Hückel results, especially much stronger onsite interaction U ∼ 0:8eV (U/t ∼ 12{15) than the Hückel estimates (U/t ∼ 7{8) as well as an appreciable longer-ranged interaction. Reexamination on physics of this family of materials is required from this realistic basis.

Original languageEnglish
Article number083710
Journaljournal of the physical society of japan
Issue number8
Publication statusPublished - 2009 Aug
Externally publishedYes


  • Downfolding
  • Effective hamiltonian
  • First-principles calculation
  • Organic conductors
  • κ-(BEDT-TTF) Cu (CN)
  • κ-(BEDT-TTF) Cu(NCS)

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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