title: Gaussian Multipole Model (GMM).
abstract: An electrostatic model based on charge density is proposed as a model for future force fields. The model is composed of a nucleus and a single Slater-type contracted Gaussian multipole charge density on each atom. The Gaussian multipoles are fit to the electrostatic potential (ESP) calculated at the B3LYP/6-31G* and HF/aug-cc-pVTZ levels of theory and tested by comparing electrostatic dimer energies, inter-molecular density overlap integrals, and permanent molecular multipole moments with their respective ab initio values. For the case of water, the atomic Gaussian multipole moments Q(lm) are shown to be a smooth function of internal geometry (bond length and bond angle), which can be approximated by a truncated linear Taylor series. In addition, results are given when the Gaussian multipole charge density is applied to a model for exchange-repulsion energy based on the inter-molecular density overlap.
authors.affiliation: Laboratory of Structural Biology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Elking
authors.forename: G Andrés
authors.initials: GA
authors.lastname: Cisneros
authors.forename: Jean-Philip
authors.initials: JP
authors.lastname: Piquemal
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Darden
authors.forename: Lee G
authors.initials: LG
authors.lastname: Pedersen