Ground-state phase diagram of the one-dimensional Hubbard model with an alternating chemical potential

Otsuka, Hiromi; Nakamura, Masaaki

doi:10.1103/physrevb.71.155105

Cited by 35 publications

(42 citation statements)

References 58 publications

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“…In particular, intensive analytical and numerical efforts have been performed to analyze the band insulator (BI) to Mott insulator (MI) transition in the Hubbard chain with alternating on-site energies. 19,20,21,22,23,24 These studies show that the halffilled ionic Hubbard chain has two transitions as U is increased. The first is from the BI to a bond-ordered, spontaneously dimerized, ferroelectric insulator (FI).…”

Section: Ref 1) One Important Results Of the Dmft Is The Descriptionmentioning

confidence: 85%

Insulator-metal-insulator transition and selective spectral-weight transfer in a disordered strongly correlated system

2006

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We investigate the metal insulator transitions at finite temperature for the Hubbard model with diagonal alloy disorder. We solve the dynamical mean field theory equations with the non crossing approximation and we use the coherent potential approximation to handle disorder. The excitation spectrum is given for various correlation strength U and disorder. Two successive metal insulator transitions are observed at integer filling values as U is increased. An important selective transfer of spectral weight arises upon doping. The strong influence of the temperature on the low energy dynamics is studied in details.

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Section: Ref 1) One Important Results Of the Dmft Is The Descriptionmentioning

confidence: 85%

Insulator-metal-insulator transition and selective spectral-weight transfer in a disordered strongly correlated system

2006

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“…The unit of energy is chosen as t = 1. For U c we have also tested an extrapolation with 1/L 3 dependence, 19 but the results were significantly inferior and displayed larger errors. For ∆ > 2 the error in the extrapolated value of U c obtained from the condition z c L = 0 is an order of magnitude larger than that obtained from the MCEL.…”

Section: 4647mentioning

confidence: 99%

Quantum phase diagram of the generalized ionic Hubbard model forABnchains

et al. 2006

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We investigate the ground-state phase diagram of the Hubbard model for the ABN−1 chain with filling 1/N , where N is the number of atoms per unit cell. In the strong-coupling limit, a charge transition takes place from a band insulator (BI) to a correlated insulator (CI) for increasing on-site repulsion U and positive on-site energy difference ∆ (energy at A sites lower than at B sites). In the weak-coupling limit, a bosonization analysis suggests that for N > 2 the physics is qualitatively similar to the case N = 2 which has already been studied: an intermediate phase emerges, which corresponds to a bond-ordered ferroelectric insulator (FI) with spontaneously broken inversion symmetry. We have determined the quantum phase diagram for the cases N = 3 and N = 4 from the crossings of energy levels of appropriate excited states, which correspond to jumps in the charge and spin Berry phases, and from the change of sign of the localization parameter z c L . From these techniques we find that, quantitatively, the BI and FI phases are broader for N > 2 than when N = 2, in agreement with the bosonization analysis. Calculations of the Drude weight and z c L indicate that the system is insulating for all parameters, with the possible exception of the boundary between the BI and FI phases.

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“…Despite the many efforts the controversy concerning the number of transitions was not resolved until recently [23,26,27]. The difficulty can be seen from Fig.…”

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confidence: 99%

Two-Site Entropy and Quantum Phase Transitions in Low-Dimensional Models

2006

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We propose a new approach to study quantum phase transitions in low-dimensional lattice models. It is based on studying the von Neumann entropy of two neighboring central sites in a long chain. It is demonstrated that the procedure works equally well for fermionic and spin models, and the two-site entropy is a better indicator of quantum phase transition than calculating gaps, order parameters or the single-site entropy. The method is especially convenient when the density-matrix renormalization-group (DMRG) algorithm is used.PACS numbers: 71.10. Fd, 71.30.+h, 75.10.Jm The search for ground state and the study of quantum phase transitions (QPTs) is a challenging problem when strongly correlated fermionic or spin systems are considered. Since exactly solvable models are rare, in most cases the relevant part of the excitation spectrum, the order parameters characterizing the various phases, or eventually susceptibilities are determined numerically on finite chains and their thermodynamic limit is determined using the standard finite-size scaling method. Unfortunately in several cases no definite conclusions can be drawn even if the calculations are performed on rather long chains.In this letter, we propose a new approach to detect QPTs and to locate the quantum critical point in lowdimensional spin or fermionic models. It is based on studying the behavior of the von Neumann entropy of two neighboring sites in the middle of a long chain, which can be defined both for fermionic and spin models, and can be especially easily implemented when the densitymatrix renormalization-group (DMRG) algorithm [1] is used.The method is closely related to concepts in quantum information theory, which recently have attracted great attention in relation to QPTs. Wu et al. [2] have shown that quite generally QPTs are signalled by a discontinuity in some measure of entanglement in the quantum system. One such measure is the concurrence [3] which has been used by a number of authors [4,5,6,7,8,9,10] in their study of spin models. Since the concurrence is defined for spin-1/2 systems only, for higher spins or fermionic models another measure of entanglement is needed.The local measure of entanglement, the one-site entropy, which is obtained from the reduced density matrix ρ i at site i, has been proposed by Zanardi [11] and Gu et al.[12] to identify QPTs. Contrary to their expectation, in many cases, this quantity turns out to be insensitive to QPT. As an example let us consider the most general isotropic spin-1 chain model described by the HamiltonianIn 1D, the model can be solved exactly at θ = ±π/4 and θ = ±3π/4, and is known to have at least four different phases [13]. The ground state is ferromagnetic for θ < −3π/4 and θ > π/2, while in between the integrable points separate the Haldane phase, which exists in the range −π/4 < θ < π/4, from the dimerized and the quantum spin nematic phases, respectively. The existence of another phase, the quantum quadrupolar phase [14] near θ = −3π/4 is not settled yet [15]. These phases and the...

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Ground-state phase diagram of the one-dimensional Hubbard model with an alternating chemical potential

Cited by 35 publications

References 58 publications

Insulator-metal-insulator transition and selective spectral-weight transfer in a disordered strongly correlated system

Insulator-metal-insulator transition and selective spectral-weight transfer in a disordered strongly correlated system

Quantum phase diagram of the generalized ionic Hubbard model forABnchains

Two-Site Entropy and Quantum Phase Transitions in Low-Dimensional Models

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