Range Separation Combined With the Overhauser Model: Application to the H2 Molecule Along the Dissociation Curve

The combination of density-functional theory with other approaches to the many-electron problem through the separation of the electron–electron interaction into a short-range and a long-range contribution (range separation) is a successful strategy, which is raising more and more interest in recent years. We focus here on a range-separated method in which only the short-range correlation energy needs to be approximated, and we model it within the “extended Overhauser approach.” We consider the paradigmatic case of the H2 molecule along the dissociation curve, finding encouraging results. By means of very accurate variational wavefunctions, we also study how the effective electron–electron interaction appearing in the Overhauser model should be to yield the exact correlation energy for standard Kohn-Sham density functional theory. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem 109: 1950–1961, 2009