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

Kazuma Nakamura; Yoshihide Yoshimoto; Taichi Kosugi; Ryotaro Arita; Masatoshi Imada

doi:10.1143/JPSJ.78.083710

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 journal › Article › peer-review

135 Citations (Scopus)

Abstract

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 language	English
Article number	083710
Journal	journal of the physical society of japan
Volume	78
Issue number	8
DOIs	https://doi.org/10.1143/JPSJ.78.083710
Publication status	Published - 2009 Aug
Externally published	Yes

Keywords

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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title = "Ab initio derivation of low-energy model for κ-ET type organic conductors",

abstract = "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 H{\"u}ckel results, especially much stronger onsite interaction U ∼ 0:8eV (U/t ∼ 12{15) than the H{\"u}ckel 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.",

keywords = "Downfolding, Effective hamiltonian, First-principles calculation, Organic conductors, κ-(BEDT-TTF) Cu (CN), κ-(BEDT-TTF) Cu(NCS)",

author = "Kazuma Nakamura and Yoshihide Yoshimoto and Taichi Kosugi and Ryotaro Arita and Masatoshi Imada",

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language = "English",

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AU - Nakamura, Kazuma

AU - Yoshimoto, Yoshihide

AU - Kosugi, Taichi

AU - Arita, Ryotaro

AU - Imada, Masatoshi

PY - 2009/8

Y1 - 2009/8

N2 - 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.

AB - 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.

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KW - Effective hamiltonian

KW - First-principles calculation

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KW - κ-(BEDT-TTF) Cu (CN)

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ER -

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

Abstract

Keywords

ASJC Scopus subject areas

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