Quantum renormalization group for the xxz model in the presence of an external magnetic field

Abstract

The anisotropic s = 1 2 antiferromagnetic Heisenberg chain in the presence of an external magnetic field is studied by using the standard quantum renormalization group. The critical line of the transition from the partially magnetized (PM) phase to the saturated ferromagnetic (SFM) phase is obtained with a very good agreement with the known exact results. The critical exponents, ground state energy, magnetization curve and correlation functions are also calculated. Our results show that the standard RG approach yields fairly good values for the critical points and their exponents.