On the coupling of multi-configuration self-consistent-field and density-functional information

Multi-configuration self-consistent-field (MCSCF) wavefunctions are often well approximated by valence-bond (VB) type functions the spatial part of which consists of a single product of non-orthogonal orbitals. On the other hand, density-functional theory (DFT) provides a means of approximately calculating dynamical correlation corrections for determinants consisting of such orbitals. Combining the two sources of information yields rather accurate results for complete potential-energy curves, as shown at the examples of the H2, HF, F2, C2, and N2 molecules.