An interesting property of the Perdew–Wang 91 density functional

The decomposition of the interaction energies is compared for fragment-based Density Functional Theory and Symmetry-Adapted Perturbation theory (SAPT). From a multitude of different functionals we obtain for hydrogen-bonded model systems a close numerical coincidence between the Pauli repulsion using the Perdew–Wang 91 functional and the correlated SAPT van der Waals terms (exchange repulsion and dispersion).