paper

Ab initio Derivation of Low-Energy Model for -ET Type Organic Conductors

arXiv:0903.5409 · doi:10.1143/JPSJ.78.083710

Abstract

We derive effective Hubbard-type Hamiltonians of -(ET), using an {\em 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 0.067 eV for a metal =Cu(NCS) and 0.055 eV for a Mott insulator =Cu(CN), as well as screened Coulomb interactions. It shows unexpected differences from the conventional extended Hückel results, especially much stronger onsite interaction 0.8 eV (12-15) than the Hückel estimates (7-8) as well as an appreciable longer-ranged interaction. Reexamination on physics of this family of materials is required from this realistic basis.

5 pages, 2 figures, and 1 table

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