Numerical renormalization-group study of the correlation functions of the antiferromagnetic spin 1/2 Heisenberg chain

Abstract

We use the density-matrix renormalization-group technique developed by White to calculate the spin correlation functions (S2n+I S2n)=(-1) 1 w(l,N) for isotropic Heisenberg rings up to N=70 sites. The correlation functions for large l and N are found to obey the scaling relation w(l,N) = w(l,oo)fxy(l!N) proposed by Kaplan et al., which is used to determine w(l,oo). The asymptotic correlation function w(l,oo) and the magnetic structure factor S(q=7T) show logarithmic corrections consistent with w(l,oo)~a-lncl /l, where c is related to the cut-off dependent coupling constant g .H( 10) = 1/ln(cl0), as predicted by field theoretical treatments.