DYNAMIC CORRELATIONS OF ANTIFERROMAGNETIC SPIN-1/2 XXZ CHAINS AT ARBITRARY TEMPERATURE FROM COMPLETE DIAGONALIZATION

摘要

All eigenstates and eigenvalues are determined for the spin-1/2 XXZ chain H=2J Sigma(i)((SiSi+1x)-S-x+(SiSi+1y)-S-y+Delta (SiSi+1z)-S-z) for rings with up to N=16 spins, for anisotropies Delta=0, cos(0.3 pi), and 1. The dynamic spin pair correlations [S-l+n(mu)(t)S-l(mu)], (mu=x,z), the dynamic structure factors S-mu(q,omega), and the intermediate structure factors I-mu(q,t) are calculated for arbitrary temperature T. It is found that for all T, S-z(q,omega) is mainly concentrated on the region omega