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Title: GW and Bethe-Salpeter study of small water clusters

We study within the GW and Bethe-Salpeter many-body perturbation theories the electronic and optical properties of small (H{sub 2}O){sub n} water clusters (n = 1-6). Comparison with high-level CCSD(T) Coupled-Cluster at the Single Double (Triple) levels and ADC(3) Green’s function third order algebraic diagrammatic construction calculations indicates that the standard non-self-consistent G{sub 0}W{sub 0}@PBE or G{sub 0}W{sub 0}@PBE0 approaches significantly underestimate the ionization energy by about 1.1 eV and 0.5 eV, respectively. Consequently, the related Bethe-Salpeter lowest optical excitations are found to be located much too low in energy when building transitions from a non-self-consistent G{sub 0}W{sub 0} description of the quasiparticle spectrum. Simple self-consistent schemes, with update of the eigenvalues only, are shown to provide a weak dependence on the Kohn-Sham starting point and a much better agreement with reference calculations. The present findings rationalize the theory to experiment possible discrepancies observed in previous G{sub 0}W{sub 0} and Bethe-Salpeter studies of bulk water. The increase of the optical gap with increasing cluster size is consistent with the evolution from gas to dense ice or water phases and results from an enhanced screening of the electron-hole interaction.
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. CNRS, Institut NEEL, F-38042 Grenoble (France)
  2. CEA, DEN, Service de Recherches de MĂ©tallurgie Physique, F-91191 Gif-sur-Yvette (France)
  3. Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800 (United States)
  4. (United States)
  5. INAC, SP2M/L-Sim, CEA/UJF Cedex 09, 38054 Grenoble (France)
Publication Date:
OSTI Identifier:
22493659
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 144; Journal Issue: 3; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BETHE-SALPETER EQUATION; COMPARATIVE EVALUATIONS; EIGENVALUES; ELECTRONIC STRUCTURE; ENERGY GAP; EV RANGE; EXCITATION; GREEN FUNCTION; HOLES; ICE; MANY-BODY PROBLEM; MOLECULAR CLUSTERS; OPTICAL PROPERTIES; PERTURBATION THEORY; WATER