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Nature of the insulating phases in the half-filled ionic Hubbard model

A. P. Kampf·M. Sekania·G. I. Japaridze·Ph. Brune
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Abstract

We investigate the ground-state phase diagram of the one-dimensional "ionic" Hubbard model with an alternating periodic potential at half-filling by numerical diagonalization of finite systems with the Lanczos and density matrix renormalization group (DMRG) methods. We identify an insulator-insulator phase transition from a band to a correlated insulator with simultaneous charge and bond-charge order. The transition point is characterized by the vanishing of the optical excitation gap while simultaneously the charge and spin gaps remain finite and equal. Indications for a possible second transition into a Mott-insulator phase are discussed.

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A. P. Kampf, M. Sekania, G. I. Japaridze, Ph. Brune. 2003-10-24. Nature of the insulating phases in the half-filled ionic Hubbard model. https://doi.org/10.1088/0953-8984%2F15%2F34%2F319

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