Journal article ยท Preprint article
Fully self-consistent GW calculations for molecules
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.
Language: | English |
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Year: | 2010 |
Pages: | 10 |
ISSN: | 1550235x , 10980121 and 01631829 |
Types: | Journal article and Preprint article |
DOI: | 10.1103/PhysRevB.81.085103 |
ORCIDs: | Jacobsen, Karsten Wedel and Thygesen, Kristian Sommer |