Predictions for water clusters from a first-principles two- and three-body force field.
A new rigid-monomer three-body potential has been developed for water by fitting it to more than 70 thousand trimer interaction energies computed ab initio using coupled-cluster methods and augmented triple-zeta-quality basis sets. This potential was used together with a modified form of a previously developed two-body potential and with a polarization model of four- and higher-body interactions to predict the energetics of the water trimer, hexamer, and 24-mer. Despite using the rigid-monomer approximation, these predictions agree better with flexible-monomer benchmarks than published results obtained with flexible-monomer force fields. An unexpected finding of our work is that simple polarization models predict four-body interactions to within a few percent, whereas for three-body interactions these models are known to have errors on the order of 50%.
Institute of Chemistry, University of Silesia, Szkolna 9, 40-006 Katowice, Poland.
Urszula
U
Góra
Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA.
Wojciech
W
Cencek
Institute of Chemistry, University of Silesia, Szkolna 9, 40-006 Katowice, Poland.
Rafał
R
Podeszwa
Theoretical Chemistry, Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
Ad
A
van der Avoird
Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA.
Krzysztof
K
Szalewicz