  A new empirical potential for efficient, large scale molecular dynamics
simulation of water is presented. The HIPPO (Hydrogen-like Intermolecular
Polarizable POtential) force field is based upon the model electron density of
a hydrogen-like atom. This framework is used to derive and parameterize
individual terms describing charge penetration damped permanent electrostatics,
damped polarization, charge transfer, anisotropic Pauli repulsion, and damped
dispersion interactions. Initial parameter values were fit to Symmetry Adapted
Perturbation Theory (SAPT) energy components for ten water dimer
configurations, as well as the radial and angular dependence of the canonical
dimer. The SAPT-based parameters were then systematically refined to extend the
treatment to water bulk phases. The final HIPPO water model provides a balanced
representation of a wide variety of properties of gas phase clusters, liquid
water and ice polymorphs, across a range of temperatures and pressures. This
water potential yields a rationalization of water structure, dynamics and
thermodynamics explicitly correlated with an ab initio energy decomposition,
while providing a level of accuracy comparable or superior to previous
polarizable atomic multipole force fields. The HIPPO water model serves as a
cornerstone around which similarly detailed physics-based models can be
developed for additional molecular species.
