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 …

We study the zero-temperature phase diagram of the half-filled one-dimensional ionic
Hubbard model. This model is governed by the interplay of the on-site Coulomb repulsion …

We discuss the nature of criticality in the β2= 2πN self-dual extension of the sine-Gordon
model. This field theory is related to the two-dimensional classical XY model with a N-fold …

Recent developments of theoretical studies on spin nanotubes are reviewed, especially
focusing on the S= 1/2 three-leg spin tube. In contrast to the three-leg spin ladder, the tube …

We consider a model of one-dimensional Mott insulators coupled by a weak interchain
tunneling t⊥. We first determine the single-particle Green's function of a single chain by …

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 …

We revisit the ground-state phase diagram of the one-dimensional half-filled extended
Hubbard model with on-site (U) and nearest-neighbor (V) repulsive interactions. In the first …

In this paper we analyze the spectral level statistics of the one-dimensional ionic Hubbard
model, the Hubbard model with an alternating on-site potential. In particular, we focus on the …

We obtain the quantum phase diagram of the ionic Hubbard model including electron-hole
symmetric density-dependent hop**. The boundaries of the phases are determined by …

We consider a system of interacting spinless fermions on a two-leg triangular ladder with π/2
magnetic flux per triangular plaquette. Microscopically, the system exhibits a U (1) symmetry …