Dynamics of quantum spin systems in dimer and valence-bond solid ground states stabilized by competing interactions

TL;DR

This paper investigates the dynamics of quantum spin chains with special ground states, using recursion methods to analyze their spin excitation spectra and revealing new insights into their line shapes and dispersions.

Contribution

It applies the recursion method to compute the spin dynamic structure factor for specific quantum spin models with exact ground states, providing novel results on their spectral properties.

Findings

New line shape characterizations of spin excitations

Dispersions relevant to dimer and valence-bond-solid states

Enhanced understanding of quantum spin dynamics

Abstract

For special coupling ratios, the one-dimensional (1D) s=1/2 Heisenberg model with antiferromagnetic nearest and next-nearest neighbor interactions has a pure dimer ground state, and the 1D s=1 Heisenberg model with antiferromagnetic bilinear and biquadratic interactions has an exact valence-bond-solid ground state. The recursion method is used to calculate the T=0 spin dynamic structure factor for both models and, for the s=1/2 model, also the dimer dynamic structure factor. New results for line shapes and dynamically relevant dispersions are obtained.