We report spin wave and density-matrix renormalization-group (DMRG) studies of the
ground and low-lying excited states of uniform and dimerized alternating spin chains. The …

The S= 1 quantum antiferromagnetic chain with the Hamiltonian H= J i S ix S i+ 1 x+ S iy S i+
1 y+ λ S iz S i+ 1 z+ D (S iz) 2 is studied. By developing a (path-integral-type) stochastic …

We propose an order parameter to characterize valence-bond-solid (VBS) states in quantum
spin chains, given by the ground-state expectation value of a unitary operator appearing in …

We study the S= 1 quantum spin chain with bond alternation H=∑ i (1-(-1) i δ) S i· S i+ 1 by
the density matrix renormalization group method recently proposed by White (Phys. Rev …

The structure of edge states in general finite antiferromagnetic quantum spin chains with
arbitrary spin value S is discussed within the framework of the nonlinear-sigma model …

Ultrafast photoinduced phase transition in a spin-Peierls (SP) system of K-
tetracyanoquinodimethane (K-TCNQ) was studied by femtosecond (fs) reflection …

We use a tensor network renormalization group method to study random S= 2
antiferromagnetic Heisenberg chains with alternating bond strength distributions. In the …

Critical properties of the spin-1 bond-alternating XXZ chain are studied numerically. This
model is appropriate to study the VBS picture and hidden Z 2× Z 2 symmetry concerning to …

Thermodynamic properties of a tetramer ferro-ferro-antiferro-antiferromagnetic Ising-
Heisenberg bond-alternating chain are investigated by the use of an exact mapping …

Ground-state properties of S= 1 antiferromagnetic Heisenberg chains with bond alternation,
H= J∑ i {1-(-1) i δ} S i· S i+ 1, are studied by a quantum Monte Carlo method. Spin …