title: Charge Transfer Models of Zinc and Magnesium in Water.
abstract: Quantum mechanical studies point to the importance of polarization and charge transfer (CT) in zinc binding. A new CT force field is used to study these effects in ion-water dimers and in aqueous solution. Quantum mechanics calculations are carried out to determine amounts of CT. Models for zinc and magnesium are parametrized to reproduce solvation structure, hydration free energy, and CT properties. The new models are subjected to energy decomposition, in which the effects of polarization and CT are investigated. The importance of these multibody interactions in the liquid is also considered. We find that, for divalent cations, polarization and charge transfer both strongly affect binding to water. Though polarization increases the internal (self) energy of water and ions, this is more than compensated for by a stronger ion-water interaction energy. The direction of the charge transfer from the water to the cation weakens the ion-water interaction; this increase in energy is counteracted by a decrease in the system energy due to electron delocalization.
authors.affiliation: Department of Chemistry, University of New Orleans , New Orleans, Louisiana 70148, United States.
authors.forename: Marielle
authors.initials: M
authors.lastname: Soniat
authors.affiliation: Benjamin Franklin High School , New Orleans, Louisiana 70122, United States.
authors.forename: Lisa
authors.initials: L
authors.lastname: Hartman
authors.affiliation: Department of Chemistry, University of New Orleans , New Orleans, Louisiana 70148, United States.
authors.forename: Steven W
authors.initials: SW
authors.lastname: Rick