Molecular dynamics simulations of aqueous solutions require a high quality water potential. We have combined the frozen-core (Coulomb and exchange-repulsion) terms of the Gaussian Electrostatic Model (GEM) with the polarization and Van der Waals terms of AMOEBA to form a new hybrid GEM/AMOEBA potential. The advantage of this combined potential is that the Coulomb and exchange-repulsion terms are calculated from frozen densities with very high accuracy. All terms are fitted to reproduce the full QM intermolecular interactions at the MP2/6-311++G(2d,2p) level (HF/6-311++G(2d,2p) for exchange-repulsion and polarization). The damped Halgren used for the Van der Waals term has been fitted by means of a new approach that optimizes the parameters using dimer interaction energies and selected bulk properties. The performance of the GEM/AMOEBA model compared to the original AMOEBA potential with respect to experimental properties including water liquid density ?w, liquid structure, enthalpy of vaporization ?Hvap, and water self diffusion coefficient Dw will be discussed.

Towards an accurate water potential: Parametrization of a combined GEM/AMOEBA model

246th National Meeting (2013)

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