Abstract :
The ground-state properties of a chain of squares, with at every corner of a square an particle and doped with two holes, have been studied in the antiferromagnetic Heisenberg model. The ground-state energies, staggered magnetisation and spin-spin correlations are given, using different basis sets. These data have been analyzed in terms of a magnetic contribution to the interaction of the two holes. An attractive interaction between the holes has been found and ascribed to resonance. This resonance has been quantified in terms of sizes of subsets of the basis set, classified by the number of singlet bonds along an exchange interaction.
