Abstract
The single-particle spectral-weight function of the ionic Hubbard model (IHM) at half-fillingshows an abrupt change of regime at a critical value of the coupling constant (HubbardU). Specifically, this function jumps at the Fermi pointskF = ± π/2 from a two-peak to a four-peak structure accompanied by a (non-vanishing) minimum of thesingle-particle charge gap. This jump separates a weak-coupling regime, the band insulatingphase, from a strong-coupling regime which evolves gradually into the Mott–Hubbardphase. We take advantage of this critical behaviour to model several quasi-one-dimensionalmaterials in terms of the IHM instead of the simpler one-band Hubbard model. For instance,the two regimes are physically realized in the angle-resolved photoelectron spectra of(TaSe4)2I, and theblue-bronze K0.3MoO3, respectively.
Published Version
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