arXiv:cond-mat/9809405 · Journal of Physics A Mathematical and General
Exact diagonalization of theS= 1/2 Heisenberg antiferromagnet on finite bcc lattices to estimate properties on the infinite lattice
Donald D. Betts, J. Schulenburg, G.E. Stewart, Johannes Richter, James Flynn
Abstract
This paper is the third in a sequence of papers developing and applying the finite-lattice method for estimation of the zero-temperature properties of quantum spin models on infinite cubic lattices. Here we generate finite bipartite body-centred cubic (bcc) lattices of vertices. Our geometrically distinct finite lattices are defined by vectors in upper triangular lattice form. We have found that sets of two to six geometrically distinct finite bcc lattices are topologically identical, and that we thus need only one lattice of each set for our method of estimation. We have studied the spin one-half Heisenberg antiferromagnet by diagonalizing its Hamiltonian on each of the finite lattices and hence computing its ground-state properties. By extrapolation of these data we obtain estimates of the T = 0 properties on the infinite bcc lattice. Our estimate of the T = 0 energy agrees to five parts in 10 thousand with third-order spin-wave and series-expansion method estimates, while our estimate of the staggered magnetization agrees with the spin-wave estimate to within 0.25%.