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TT: Fachverband Tiefe Temperaturen
TT 10: Focused Session: Frontiers of Electronic Structure Theory 1 (jointly with HL and O)
TT 10.7: Vortrag
Montag, 11. März 2013, 12:15–12:30, H36
The bond-breaking and bond-making puzzle: many-body perturbation versus density-functional theory — •F. Caruso1, D. Rohr2, M. Hellgren3, X. Ren1, P. Rinke1, A. Rubio4,1, and M. Scheffler1 — 1Fritz-Haber-Institut, Berlin, Germany — 2Rice University, Houston, USA — 3SISSA, Trieste, Italy — 4Universidad del Pais Vasco, Donostia, Spain
Diatomic molecules at dissociation provide a prototypical situation in which the ground-state cannot be described by a single Slater determinant. For the paradigmatic case of H2-dissociation we compare state-of-the-art many-body perturbation theory in the GW approximation and density-functional theory (DFT) in the exact-exchange plus random-phase approximation for the correlation energy (RPA). Results from the recently developed renormalized second-order perturbation theory (rPT2) are also reported. For an unbiased comparison and to prevent spurious starting point effects both RPA and GW are iterated to full self-consistency (i.e. sc-RPA and sc-GW). Both include topologically identical diagrams for the exchange and correlation energy but are evaluated with a non-interacting Kohn-Sham and an interacting GW Green function, respectively. This has profound consequences for the kinetic and the correlation energy. GW and rPT2 are both accurate at equilibrium, but fail at dissociation, in contrast to sc-RPA. This failure demonstrates the need of including higher order correlation diagrams in sc-GW. Our results indicate that RPA-based DFT is a strong contender for a universally applicable electronic-structure theory. F. Caruso et al. arxiv.org/abs/1210.8300.