Hydrogen-Bonding Polarizable Intermolecular Potential Model for Water

A polarizable intermolecular
potential model with short-range directional
hydrogen-bonding interactions was developed for water. The model has
a rigid geometry, with bond lengths and angles set to experimental
gas-phase values. Dispersion interactions are represented by the Buckingham
potential assigned to the oxygen atom, whereas electrostatic interactions
are modeled by Gaussian charges. Polarization is handled by a Drude
oscillator site, using a negative Gaussian charge attached to the
oxygen atom by a harmonic spring. An explicit hydrogen-bonding term
is included in the model to account for the effects of charge transfer.
The model parameters were optimized to density, configurational energy,
pair correlation function, and the dielectric constant of water under
ambient conditions, as well as the minimum gas-phase dimer energy.
Molecular dynamics and Gibbs ensemble Monte Carlo simulations were
performed to evaluate the new model with respect to the thermodynamic
and transport properties over a wide range of temperature and pressure
conditions. Good agreement between model predictions and experimental
data was found for most of the properties studied. The new model yields
better performance relative to the majority of existing models and
outperforms the BK3 model, which is one of the best polarizable models,
for vapor–liquid equilibrium properties, whereas the new model
is not better than the BK3 model for representation of other properties.
The model can be efficiently simulated with the thermalized Drude
oscillator algorithm, resulting in computational costs only 3 times
higher than those of the nonpolarizable TIP4P/2005 model, whereas
having significantly improved properties. Because it involves only
a single Drude oscillator site, the new model is significantly faster
than polarizable models with multiple sites. With the explicit inclusion
of hydrogen-bond interactions, the model may provide a better description
of the phase behavior of aqueous mixtures.