Abstract
A quantum phase transition is typically induced by tuning an external parameter that appears as a coupling constant in the Hamiltonian. Another route is to vary the global symmetry of the system, generalizing, e.g., SU(2) to . In that case, however, the discrete nature of the control parameter prevents one from identifying and characterizing the transition. We show how this limitation can be overcome for the Heisenberg model with the help of a singlet projector algorithm that can treat continuously. On the square lattice, we find a direct, continuous phase transition between Néel-ordered and crystalline bond-ordered phases at with critical exponents and .
- Received 22 September 2009
DOI:https://doi.org/10.1103/PhysRevB.80.184401
©2009 American Physical Society