Next Nearest-Neighbor Correlation Functions of the Spin-1/2 XXZ Chain at Massive Region

TL;DR

This paper derives a method to evaluate next nearest-neighbor correlation functions in the spin-1/2 XXZ chain's massive region, simplifying complex integrals to enable explicit calculations.

Contribution

It introduces a reduction technique from three-dimensional to one-dimensional integrals for correlation functions in the XXZ model's massive phase.

Findings

Explicit values for next nearest-neighbor correlations for Δ > 1

Reduction of complex integrals to simpler forms

Enhanced computational approach for spin chain correlations

Abstract

The second neighbor correlation functions of the spin-${{1/2}}$ $XXZ$ chain in the ground state are expressed in the form of three dimensional integrals. We show that these integrals can be reduced to one-dimensional ones and thereby evaluate the values of the next nearest-neighbor correlation functions for ${\Delta >1}$.