### Abstract

We calculate single-particle excitation energies for a series of 34 molecules using fully self-consistent GW, one-shot G0W0, Hartree-Fock (HF), and hybrid density-functional theory (DFT). All calculations are performed within the projector-augmented wave method using a basis set of Wannier functions augmented by numerical atomic orbitals. The GW self-energy is calculated on the real frequency axis including its full frequency dependence and off-diagonal matrix elements. The mean absolute error of the ionization potential (IP) with respect to experiment is found to be 4.4, 2.6, 0.8, 0.4, and 0.5 eV for DFT-PBE, DFT-PBE0, HF, G0W0[HF], and self-consistent GW, respectively. This shows that although electronic screening is weak in molecular systems, its inclusion at the GW level reduces the error in the IP by up to 50% relative to unscreened HF. In general GW overscreens the HF energies leading to underestimation of the IPs. The best IPs are obtained from one-shot G0W0 calculations based on HF since this reduces the overscreening. Finally, we find that the inclusion of core-valence exchange is important and can affect the excitation energies by as much as 1 eV.

Original language | English |
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Journal | Physical Review B Condensed Matter |

Volume | 81 |

Issue number | 8 |

Pages (from-to) | 085103 |

ISSN | 0163-1829 |

DOIs | |

Publication status | Published - 2010 |

### Bibliographical note

Copyright 2010 American Physical Society## Cite this

Rostgaard, C., Jacobsen, K. W., & Thygesen, K. S. (2010). Fully self-consistent GW calculations for molecules.

*Physical Review B Condensed Matter*,*81*(8), 085103. https://doi.org/10.1103/PhysRevB.81.085103