REAL-SPACE RENORMALIZATION-GROUP APPROACH TO THE 2D ANTIFERROMAGNETICHEISENBERG-MODEL

We apply real-space RG techniques to study the quantum two-dimensional antiferromagnetic Heisenberg model for arbitrary values of the spin S on a square lattice. We introduce a 5-block truncation scheme which y ields complete analytical results for renormalizing spin factors, grou nd state energy and non-zero staggered magnetization. Our RG-flow equa tions show that the 2D model remains massless For All S. We propose th at the valence bonds forming the ground state of the 2D-AF Heisenberg model on a square lattice rotate under the effect of the antiferromagn etic background.