Related papers: On the correllation effect in Peierls-Hubbard chai…
The spin one-half Heisenberg chain with $U_q[SU(2)]$ symmetry is studied via density-matrix renormalization. Ground-state energy and $q$-symmetric correlation functions are calculated for the non-hermitian case $q=\exp(i\pi/(r+1))$ with…
The ground-state phase diagram of the frustrated spin-S XXZ chain with the competing nearest- and next-nearest-neighbor antiferromagnetic couplings is studied numerically by using the density-matrix renormalization-group method for the…
The interplay between quarter-filled and half-filled umklapp scattering has been examined by applying the renormalization group method to a one-dimensional quarter-filled electron system with dimerization, on-site (U) and nearest-neighbor…
We describe a new path integral approach to strongly correlated fermion systems, considering the Hubbard model as a specific example. Our approach is based on the introduction of spin-particle-hole coherent states which generalize the…
The dynamical density-matrix renormalization group technique is used to calculate spin and charge excitation spectra in the one-dimensional (1D) Hubbard model at quarter filling with nearest-neighbor $t$ and next-nearest-neighbor $t'$…
Exploiting the matrix-product-state based density-matrix renormalization group (DMRG) technique we study the one-dimensional extended ($U$-$V$) Hubbard model with explicit bond dimerization in the half-filled band sector. In particular we…
Complementarity - the absence of a phase boundary separating the Higgs and confinement phases of a gauge theory - can be violated by the addition of chiral fermions. We utilize chiral symmetry violating fermion correlators such as $ \langle…
We establish a direct connection between inhomogeneous XX spin chains (or free fermion systems with nearest-neighbors hopping) and certain QES models on the line giving rise to a family of weakly orthogonal polynomials. We classify all such…
Density matrix renormalization group methods are used to investigate the quantum phase diagram of a one-dimensional half-filled ionic Hubbard model with bond-charge attraction, which can be mapped from the Su-Schrieffer-Heeger-type…
We study the spin-1/2 chain with nearest neighbor ($\kappa_1$) and next-nearest neighbor ($\kappa_2$) interactions in the regime $\kappa_2\gg \kappa_1$, which is equivalent to two chains with a `zig-zag' interaction. In the continuum limit,…
The density-matrix renormalization group (DMRG) is employed to calculate optical properties of the half-filled Hubbard model with nearest-neighbor interactions. In order to model the optical excitations of oligoenes, a Peierls dimerization…
We study the half-chain entanglement entropy in the ground state of the spin-1/2 XX chain across an extended random defect, where the strength of disorder decays with the distance from the interface algebraically as $\Delta_l\sim…
Key properties of a physical system depend on whether it is gapped, i.e. whether its spectral gap has a positive lower bound that is independent of system size. In quantum information theory, the question of whether a system is gapped has…
Two very different methods -- exact diagonalization on finite chains and a variational method -- are used to study the possibility of a metal-insulator transition in the symmetric half-filled periodic Anderson-Hubbard model. With this aim…
The effect of Hubbard and Kondo interactions on the edge states in the half-filled Su-Schrieffer-Heeger chain of electrons is investigated by studying the behaviour of charge quasiparticles using Kumar representation and density matrix…
We study spontaneous dimerization transitions in a Heisenberg spin-1 chain with additional next-nearest neighbor (NNN) and 3-site interactions using extensive numerical simulations and a conformal field theory analysis. We show that the…
Though most fermionic Mott insulators order at low temperatures, ordering is ancillary to their insulating behaviour. Our emphasis here is on disentangling ordering from the intrinsic strongly correlated physics of a doped half-filled band.…
We establish dimerization in $O(n)$-invariant quantum spin chains with big enough $n$, in a large part of the phase diagram where this result is expected. This includes identifying two distinct ground states which are translations of one…
A modification of perturbation theory, known as delta-expansion (variationally improved perturbation), gave rigorously convergent series in some D=1 models (oscillator energy levels) with factorially divergent ordinary perturbative…
We use the Density-Matrix Renormalization Group to study the single-particle and two-particle correlation functions of spinless fermions in the ground state of a quarter-filled ladder. This ladder consists of two chains having an in-chain…