Static spin correlations in singlet states via triplet overlap integrals

Abstract

An efficient method for the calculation of static spin-spin correlation matrix elements between singlet states is described. The method uses the property that the site spin operator s^XXX_p converts a singlet diagram with a line through a site p into a triplet diagram with an arrow through the site p. The method can easily be extended to other spin states as well as to more than two spin correlations. This method would be valuable in cases where charge orthogonality of the VB diagrams alone cannot reduce the computations to a managable extent.