# Berlin 2012 – wissenschaftliches Programm

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# O: Fachverband Oberflächenphysik

## O 73: Focussed session: Frontiers of electronic structure theory: Strong correlations from first principles V (jointly with TT)

### O 73.1: Topical Talk

### Donnerstag, 29. März 2012, 16:00–16:30, HE 101

**Symmetry Breaking and Restoration in Electronic Structure Theory** — •Gustavo Scuseria — Rice University, Houston, Texas, USA

We have derived and implemented symmetry-projected Hartree-Fock-Bogoliubov (HFB) equations and apply them to the molecular electronic structure problem. All symmetries (particle number, spin, spatial, and complex conjugation) are deliberately broken and restored in a self-consistent variation-after-projection approach. We show that the resulting method yields a comprehensive black-box treatment of static correlation with effective one-electron (mean-field) computational cost. The ensuing wave function is of multireference character and permeates the entire Hilbert space of the problem. The energy expression is an independent quasiparticle density matrix functional. All reduced density matrices are expressible as an integration of transition one-particle density matrices over a gauge grid. I will present several proof-of-principle examples demonstrating the compelling power of this new method for electronic structure theory [1].

[1] Projected Quasiparticle Theory for Molecular Electronic Structure, G. E. Scuseria, C. A. Jimenez-Hoyos, T. M. Henderson, J. K. Ellis, and K. Samanta, J. Chem. Phys. 135, 124108 (2011).