title: Dispersion Interactions in Water Clusters.
abstract: The importance of dispersion forces in water clusters is examined using the effective fragment potential (EFP) method. Since the original EFP1 water potential does not include dispersion, a dispersion correction to the EFP1 potential (EFP1-D) was derived and implemented. The addition of dispersion to the EFP1 potential yields improved geometries for water clusters that contain 2-6 molecules. The importance of the odd E7contribution to the dispersion energy is investigated. The E7dispersion term is repulsive for all of the water clusters studied here and can have a magnitude that is as large as half of the E6value. The E7term therefore contributes to larger intermolecular distances for the optimized geometries. Inclusion of many-body effects and/or higher order terms may be necessary to further improve dispersion energies and optimized geometries.
authors.affiliation: Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Emilie B
authors.identifier: http://orcid.org/0000-0003-1961-0469
authors.initials: EB
authors.lastname: Guidez
authors.affiliation: Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Mark S
authors.identifier: http://orcid.org/0000-0001-6893-553X
authors.initials: MS
authors.lastname: Gordon