title: Ground state projection of quantum spin systems in the valence-bond basis.
abstract: A Monte Carlo method for quantum spin systems is formulated in the valence-bond basis. The nonorthogonality allows for an efficient importance-sampled projection of the ground state out of an arbitrary state. The method provides access to resonating valence-bond physics, enables a direct estimator for the singlet-triplet gap, and extends the class of models that can be studied without negative-sign problems. As a demonstration, the valence-bond distribution in the ground state of the 2D Heisenberg antiferromagnet is calculated. Generalizations of the method to fermion systems are also discussed.
authors.affiliation: Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA.
authors.forename: Anders W
authors.initials: AW
authors.lastname: Sandvik