Piecewise linearity in the GW approximation for accurate quasiparticle energy predictions

Matthias Dauth, Fabio Caruso, Stephan Kümmel, Patrick Rinke

Research output: Contribution to journalArticleScientificpeer-review

20 Citations (Scopus)
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We identify the deviation from the straight-line error (DSLE) - i.e., the spurious nonlinearity of the total energy as a function of fractional particle number - as the main source for the discrepancy between experimental vertical ionization energies and theoretical quasiparticle energies, as obtained from the GW and GW+SOSEX approximations to many-body perturbation theory (MBPT). To check whether a DSLE is present in GW, we propose an indicator that only invokes observables at integer particle numbers. For self-consistent calculations, we show that GW suffers from a small DSLE. Conversely, for perturbative G0W0 and G0W0+SOSEX calculations the DSLE depends on the starting point. We exploit this starting point dependence to reduce (or completely eliminate) the DSLE. We find that the agreement with experiment increases as the DSLE reduces. DSLE-minimized schemes thus emerge as promising avenues for future developments in MBPT.

Original languageEnglish
Article number121115
Pages (from-to)1-5
JournalPhysical Review B
Issue number12
Publication statusPublished - 31 Mar 2016
MoE publication typeA1 Journal article-refereed


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