The algorithm is described in detail and timings and scalability are reported for simulations up to 503 water molecules. The important properties of water stem from its unique structure and the way this structure allows water to interact with electrically charged molecules. Such properties are thought to arise from the ability of water to form tetrahedrally coordinated hydrogen bonds.
Water is unusual as both a liquid and a solvent.
The insertion of nonpolar solutes into water is strongly unfavorable, called the hydrophobic effect, while polar molecules dissolve freely and are characterized as hydrophilic. The 3-dimensional structure of these molecules is dictated by the way these chains fold into more compact arrangements. Hydrophilic groups are on the surface where they can interact with water, and hydrophobic groups are buried in the interior, away from water. Our algorithm, with the judicious use of fairly short range cut-offs should provide a natural next step in that direction, with a substantially better model of the short range force responsible for hydrogen bonding. The TIP4P model includes a Lennard Jones 6-12 interaction between the oxygen mass centers of the water molecules and electrostatic interactions between the charged sites.