# Berlin 2012 – wissenschaftliches Programm

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# O: Fachverband Oberflächenphysik

## O 84: Focussed session: Frontiers of electronic structure theory: Strong correlations from first principles VI (jointly with TT)

### O 84.7: Vortrag

### Freitag, 30. März 2012, 12:15–12:30, HE 101

**Unified description of ground and excited states of finite systems: the self-consistent ***GW*** approach** — •Fabio Caruso^{1}, Patrick Rinke^{1}, Xinguo Ren^{1}, Angel Rubio^{1,2}, and Matthias Scheffler^{1} — ^{1}Fritz-Haber-Institut, Berlin, Germany — ^{2}Universidad del Pais Vasco, San Sebastian, Spain

Fully
self-consistent *GW* calculations – based on the iterative solution of the
Dyson equation – provide an approach for consistently describing ground
and excited states on the same quantum mechanical level.
Based on our implementation in the all-electron localized basis code FHI-aims
[1], we show that for finite systems self-consistent *GW* reaches the same final
Green function regardless of the starting point.
The results show that self-consistency systematically improves ionization
energies and total energies of closed shell systems compared to perturbative *GW*
calculations (*G*_{0}*W*_{0}) based on Hartree-Fock or (semi)local density-functional
theory. These improvements also translate to the electron density
as demonstrated by a better description of the dipole moments of hetero-atomic
dimers and the similarity with the coupled cluster singles doubles (CCSD) density.
The starting-point independence of the self-consistent Green function
facilitates a systematic and unbiased assessment of the performance of the *GW*
approximation for finite systems.
It therefore constitutes an unambiguous reference for the future
development of vertex corrections and beyond *GW* schemes.

[1] V. Blum *et al.*, Comp. Phys. Comm. **180**, 2175
(2009).