Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Correlated valence bond state and its study of the spin-1/2 J1-J2
  Anti-ferromagnetic Heisenberg model on a square lattice   We propose a class of variational wave functions, namely the correlated
valence bond states, for the frustrated Hamiltonian in the paramagnetic phase.
This class of wave functions admits negative amplitude and the same sub-lattice
pairing when a bipartite lattice is considered, thus suffers from the negative
sign problem. However if applied to small systems, the sign problem is
manageable using the standard variational Monte Carlo method. We optimize the
wave functions for the J1-J2 Anti ferromagnetic Heisenberg model on a square
lattice in the coupling region J2/J1 \in [0.45 : 0.56] for system sizes L = 4,
6, 8. To calculate the correlation functions and the order parameters for
larger systems, we make the extensive Monte Carlo samplings using the
variational parameters optimized at system size L = 8. We find that the
paramagnetic phase is a gap-less spin liquid in the entire range of J2/J1 \in
[0.45 : 0.56] with a gap-less singlet excitation and a gaped triplet
excitation.

29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph