Year: 2010
Type: article
Abstract: We calculate single-particle excitation energies for a series of 34 molecules using fully self-consistent GW, one-shot ${\text{G}}_{0}{\text{W}}_{0}$, 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, ${\text{G}}_{0}{\text{W}}_{0}[\text{HF}]$, 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 ${\text{G}}_{0}{\text{W}}_{0}$ 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.
Source: Physical Review B
Authors: C. Rostgaard, K. W. Jacobsen, K. S. Thygesen
Institution: Technical University of Denmark
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: Lundbeckfonden, H. Lundbeck A/S
OpenAlex ID: W1998254538