Volume 76, Number 2, October 2006
|Page(s)||298 - 304|
|Section||Condensed matter: electronic structure, electrical, magnetic, and optical properties|
|Published online||20 September 2006|
Fully self-consistent GW calculations for atoms and molecules
Rijksuniversiteit Groningen, Materials Science Centre, Theoretical Chemistry Nijenborgh 4, 9747AG Groningen, The Netherlands
Accepted: 29 August 2006
We solve the Dyson equation for atoms and diatomic molecules within the GW approximation, in order to elucidate the effects of self-consistency on the total energies and ionization potentials. We find GW to produce accurate energy differences although the self-consistent total energies differ significantly from the exact values. Total energies obtained from the Luttinger-Ward functional with simple, approximate Green functions as input, are shown to be in excellent agreement with the self-consistent results. This demonstrates that the Luttinger-Ward functional is a reliable method for testing the merits of different self-energy approximations without the need to solve the Dyson equation self-consistently. Self-consistent GW ionization potentials are calculated from the Extended Koopmans Theorem, and shown to be in good agreement with the experimental results. We also find the self-consistent ionization potentials to be often better than the non-self-consistent values. We conclude that GW calculations should be done self-consistently in order to obtain physically meaningful and unambiguous energy differences.
PACS: 71.15.-m – Methods of electronic structure calculations / 31.15.Lc – Quasiparticle methods
© EDP Sciences, 2006
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