Using the density-matrix renormalization group, we investigate the critical behavior of the anisotropic Heisenberg chains with spins up to
s=9/2. We show that through the relations arising from the conformal invariance and the DMRG technique it is possible to obtain accurate finite-size estimates of the conformal anomaly
c, the sound velocity
vs, the anomalous dimension
xbulk, and the surface exponent
xs of the anisotropic spin-
s Heisenberg chains with relatively good accuracy without fitting parameters. Our results indicate that the entanglement entropy
S(L,lA,s) of the spin-
s Heisenberg chains satisfies the relation $S(L,{l}_{A},s)\ensuremath{-}S(L,{l}_{A},s\ensuremath{-}1)=1/(2s+1)$ for
s>3/2 in the thermodynamic limit.
Using the density-matrix renormalization-group technique we study the long-wavelength properties of the spin
S=3/2 nearest-neighbor Heisenberg chain. We obtain an accurate value for the spin velocity $v\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3.87\ifmmode\pm\else\textpm\fi{}0.02$, in agreement with experiment. Our results show conclusively that the model belongs to the same universality class as the
S=1/2 Heisenberg chain, with a conformal central charge
c=1 and critical exponent $\ensuremath{\eta}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$.