Precise estimation of the S = 2 Haldane gap by numerical diagonalization

TL;DR

This paper accurately estimates the S=2 Haldane gap in a one-dimensional Heisenberg antiferromagnet using advanced numerical diagonalization techniques with convergence acceleration.

Contribution

It introduces a multistep convergence-acceleration method to precisely determine the Haldane gap from finite-size data.

Findings

Precise estimate of the S=2 Haldane gap achieved

Demonstrates effectiveness of convergence-acceleration in numerical diagonalization

Provides a benchmark for future theoretical and numerical studies

Abstract

The Haldane gap of the S=2 Heisenberg antiferromagnet in a one-dimensional linear chain is examined by a numerical-diagonalization method. A precise estimate for the magnitude of the gap is successfully obtained by a multistep convergence-acceleration procedure applied to finite-size diagonalization data under the twisted boundary condition.