Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 85: Frontiers of Electronic Structure Theory: Many-Body Effects on the Nano-Scale VI
O 85.1: Hauptvortrag
Donnerstag, 19. März 2015, 15:00–15:30, MA 004
Natural orbital functional theory with higher-order occupation probabilities — •Ralph Gebauer1, Roberto Car2, and Morrel Cohen2,3 — 1International Centre for Theoretical Physics (ICTP), Trieste, Italy — 2Department of Chemistry, Princeton University, Princeton, USA — 3Department of Physics and Astronomy, Rutgers University, USA
We introduce a novel energy functional for ground-state electronic-structure calculations. Its fundamental variables are the natural spin-orbitals of the implied singlet many-body wave function and their joint occupation probabilities. The functional derives from a sequence of controlled approximations to the two-particle density matrix. Algebraic scaling of computational cost with electron number is obtainable in general, and Hartree-Fock scaling in the seniority-zero version of the theory. Results obtained with the latter version for saturated small molecular systems are compared with those of highly-accurate quantum-chemical computations. The numerical results are variational, capturing most of the correlation energy from equilibrium to dissociation. Their accuracy is considerably greater than that obtainable with current density-functional theory approximations and with current functionals of the one-particle density matrix only.