Regensburg 2013 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 22: Focused Session: Frontiers of Electronic Structure Theory 2 (jointly with HL and O)
TT 22.6: Talk
Monday, March 11, 2013, 17:15–17:30, H36
Beyond the GW approximation: a second-order screened exchange correction — •Patrick Rinke1, Xinguo Ren1, Noa Marom2, Fabio Caruso1, and Matthias Scheffler1 — 1Fritz Haber Institute, Berlin, Germany — 2University of Texas, Austin, USA
Despite the success of the GW method in describing the photoemission spectra of solids, molecules and clusters, challenges remain. For aromatic molecules for example absolute as well as relative positions of ionisation energies and affinities are not well reproduced in perturbative G0W0 schemes with different starting points as well as in self-consistent GW [1], sometimes even giving the wrong orbital order. Motivated by renormalized second-order perturbation theory [2] for the ground-state energy, we propose a second-order screened exchange correction (SOSEX) to the GW self-energy. This correction follows the spirit of the SOSEX correction to the random-phase approximation for the electron correlation energy and reduces the self-correlation error. The performance of the GW+SOSEX scheme has been benchmarked for a set of molecular systems, including the G2 set, commonly used acceptor molecules, benzene and the azabenzene molecules. We find that the SOSEX correction improves the description of the spectral properties including the orbital order with respect to the different GW schemes, highlighting the importance of reducing the self-correlation error. [1] N. Marom et al., arXiv:1211.0416 [2] X. Ren et al., J. Mater. Sci. 47, 7447 (2012)