We have proposed an approach to solve the eigenvalue problem of the isotropic S=1/2 Heisenberg chain. Many interesting properties of the antiferromagnetic ground state have been reanalyzed by our technique. These results show our method is an appropriate technique.
Using (infinite) density-matrix renormalization-group techniques, ground-state properties of antiferromagnetic S=1 Heisenberg spin chains with exchange and single-site anisotropies in an external field are studied. The phase diagram is known to display a plenitude of interesting phases. We elucidate quantum phase transitions between the supersolid and spin-liquid phases as well as the spin-liquid and ferromagnetic phases. Analyzing spin-correlation functions in the spin-liquid phase, commensurate and (two distinct) incommensurate regions are identified.