The spin-1/2 J1–J2 Heisenberg antiferromagnet on the square lattice: Exact diagonalization for N = 40 spins
Eur. Phys. J. B, 73 1 (2010) 117-124
Published online: 25 November 2009
DOI: 10.1140/epjb/e2009-00400-4