Computational scheme for the spin-1/2 Heisenberg antiferromagnet based on an octapartite description of the square lattice

We introduce a parameterization of the Hilbert space of a spin-1/2 Heisenberg antiferromagnet using an octapartite description of the square lattice. This provides a systematic way to model the ground-state wave function within a truncated basis. To prove its effectiveness we study systems with up to 64 spins using exact diagonalization. At significantly reduced computational cost, we get ground-state energies within 1% of the best published values. Its noniterative nature and lack of exploitation of spatial symmetries make this approach suitable for generalization to doped systems and for integration into iterative procedures.