A reappraisal of what we have learnt during three decades of computer simulations on water

A simple polarizable water model is developed and optimized for molecular dynamics simulations of the liquid phase under ambient conditions. The permanent charge distribution of the water molecule is represented by three point charges: two hydrogen sites and one additional M site positioned along the HOH bisector. Electronic induction is represented by introducing a classical charged Drude particle attached to the oxygen by a harmonic spring. The oxygen site carries an equal and opposite charge, and is the center of an intermolecular Lennard-Jones interaction. The HOH gas-phase experimental geometry is maintained rigidly and the dipole of the isolated molecule is 1.85 D, in accord with experiment. The model is simulated by considering the dynamics of an extended Lagrangian in which a small mass is attributed to the Drude particles. It is parametrized to reproduce the salient properties of liquid water under ambient conditions. The optimal model, refered to as SWM4-DP for “simple water model with four site...

A simple polarizable model of water based on classical Drude oscillators

A simple treatment for incorporating induced polarization in computer simulations is formulated on the basis of the classical Drude oscillator model. In this model, electronic induction is represented by the displacement of a charge-carrying massless particle attached to a polarizable atom under the influence of the local electric field. The traditional self-consistent field (SCF) regime of induced polarization is reproduced if these auxiliary particles are allowed to relax instantaneously to their local energy minima for any given fixed configuration of the atoms in the system. In practice, such treatment is computationally prohibitive for generating molecular dynamics trajectories because the electric field must be recalculated several times iteratively to satisfy the SCF condition, and it is important to seek a more efficient way to simulate the classical Drude oscillator model. It is demonstrated that a close approximation to the SCF regime can be simulated efficiently by considering the dynamics of a...

Modeling induced polarization with classical Drude oscillators: Theory and molecular dynamics simulation algorithm

A polarizable model of water for molecular dynamics simulations of biomolecules

Gas-expanded liquids.

All reliable sources of data for the static dielectric constant or relative permittivity of water and steam, many of them unpublished or inaccessible, have been collected, evaluated, corrected when required, and converted to the ITS‐90 temperature scale. The data extend over a temperature range from 238 to 873 K and over a pressure range from 0.1 MPa up to 1189 MPa. The evaluative part of this work includes a review of the different types of measurement techniques, and the corrections for frequency dependence due to the impedance of circuit components, and to electrode polarization. It also includes a detailed assessment of the uncertainty of each particular data source, as compared to other sources in the same range of pressure and temperature. Both the raw and the corrected data have been tabulated, and are also available on diskette. A comprehensive list of references to the literature is included.

A Database for the Static Dielectric Constant of Water and Steam

All relevant static dielectric constant data for water and steam have been collected and evaluated, and will be made available in print and in computerized form. A new formulation of the static dielectric constant or relative permittivity of water and steam has been developed. It is based on the ITS-90 temperature scale, and uses a new fundamental equation for water and steam, likewise based on this scale. It also includes our recently obtained dielectric constant data in liquid water and in saturated steam. The new formulation ranges from - 45 to + 600 &deg;C in temperature, and from 0.1 to 1189 MPa in pressure. It is based on the dipole correlation or g-factor of Alder and Harris, and formulates this factor with 10 adjustable coefficients and associated powers of reduced density and inverse reduced temperature. 

Y. Mulev

Papers

A Database for the Static Dielectric Constant of Water and Steam

The static dielectric constant of water and steam