Berlin 2015 – scientific programme

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SYME: Symposium Frontiers of Electronic Structure Theory: Many-body Effects on the Nano-Scale

SYME 7: Frontiers of Electronic Structure Theory: Many-Body Effects on the Nano-Scale VI

SYME 7.11: Talk

Thursday, March 19, 2015, 17:45–18:00, MA 004

Comparison of two self-consistent GW schemes — •Peter Koval¹, Dietrich Foerster², and Daniel Sanchez-Portal^1,3 — ¹Donostia International Physics Center, San Sebastián, Spain — ²Laboratoire Ondes et Matiére d’Aquitaine, Bordeaux, France — ³Material Physics Center, San Sebastián, Spain

GW approximation (GWA) as a competitor of DFT provides a better description of electronic structure in several respects. However, a GW calculation is more expensive than similar DFT calculation. This fact contributed to a wide usage of simpler calculations based on GWA (SEX, COSEX, plasmon-pole approximations etc.) This manyfold of approximations hampers a non-biased evaluation of merits of GWA to describe the electronic correlations. We produced a rigorous GW implementation where the only approximation is the use of localized orbitals [1]. The usage of spectral functions allowed us to realize two self-consistent GW schemes: scGW [2] and qsGW [3] in one code [4]. Furthermore, we used all-electron Gaussian basis sets that allows for a coherent comparison with quantum chemistry methods. We use coupled-cluster methods CCSD and CCSD(T) as reference and compare ionization potentials of 15 molecules. The calculations show trends in scGW and qsGW and give hints on possible sources of discrepancies/directions towards improving GWA. [1] D. Foerster, P. Koval, D. Sánchez-Portal, J. Chem. Phys. 135, 074105 (2011); [2] L. Hedin, J. Phys. Cond. Mat. 11, R489 (1999); [3] S. V. Faleev, M. van Schilfgaarde, T. Kotani, Phys. Rev. Lett. 93, 126406 (2004); [2] P. Koval, D. Foerster, D. Sánchez-Portal, Phys. Rev. B 89, 155417 (2014).