Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ground state projection of quantum spin systems in the valence bond
  basis   A Monte Carlo method for quantum spin systems is formulated in the basis of
valence bond (singlet pair) states. The non-orthogonality of this basis 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 improved 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.

2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys