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Coupled cluster benchmarks of water monomers and dimers extracted from density-functional theory liquid water: The importance of monomer
 

Summary: Coupled cluster benchmarks of water monomers and dimers extracted
from density-functional theory liquid water: The importance of monomer
deformations
Biswajit Santra,1
Angelos Michaelides,1,2,a
and Matthias Scheffler1
1
Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, Berlin 14195, Germany
2
London Centre for Nanotechnology and Department of Chemistry, University College London,
London WC1E 6BT, United Kingdom
Received 12 July 2009; accepted 3 September 2009; published online 25 September 2009
To understand the performance of popular density-functional theory exchange-correlation xc
functionals in simulations of liquid water, water monomers and dimers were extracted from a PBE
simulation of liquid water and examined with coupled cluster with single and double excitations
plus a perturbative correction for connected triples CCSD T . CCSD T reveals that most of the
dimers are unbound compared to two gas phase equilibrium water monomers, largely because
monomers within the liquid have distorted geometries. Of the three xc functionals tested, PBE and
BLYP tend to predict too large dissociation energies between monomers within the dimers. We show
that this is because the cost to distort the monomers to the geometries they adopt in the liquid is

  

Source: Alavi, Ali - Department of Chemistry, University of Cambridge

 

Collections: Chemistry