title: Development of a 3-body:many-body integrated fragmentation method for weakly bound clusters and application to water clusters (H2O)(n = 3-10, 16, 17).
abstract: A 3-body:many-body integrated quantum mechanical (QM) fragmentation method for non-covalent clusters is introduced within the ONIOM formalism. The technique captures all 1-, 2-, and 3-body interactions with a high-level electronic structure method, while a less demanding low-level method is employed to recover 4-body and higher-order interactions. When systematically applied to 40 low-lying (H(2)O)(n) isomers ranging in size from n = 3 to 10, the CCSD(T):MP2 3-body:many-body fragmentation scheme deviates from the full CCSD(T) interaction energy by no more than 0.07 kcal mol(-1) (or <0.01 kcal mol(-1) per water). The errors for this QM:QM method increase only slightly for various low-lying isomers of (H(2)O)(16) and (H(2)O)(17) (always within 0.13 kcal mol(-1) of the recently reported canonical CCSD(T)/aug-cc-pVTZ energies). The 3-body:many-body CCSD(T):MP2 procedure is also very efficient because the CCSD(T) computations only need to be performed on subsets of the cluster containing 1, 2, or 3 monomers, which in the current context means the largest CCSD(T) calculations are for 3 water molecules, regardless of the cluster size.
authors.affiliation: Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677-1848, USA.
authors.forename: Desiree M
authors.initials: DM
authors.lastname: Bates
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Smith
authors.forename: Tomasz
authors.initials: T
authors.lastname: Janowski
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Tschumper
mesh_terms: D004583:Electrons; D008956:Models, Chemical; D011789:Quantum Theory; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water